In the periodic table, group 17 contains an element that is liquid at standard temperature and pressure.
What is periodic table?Periodic table is a tabular arrangement of elements in the form of a table. In the periodic table, elements are arranged according to the modern periodic law which states that the properties of elements are a periodic function of their atomic numbers.
It is called as periodic because properties repeat after regular intervals of atomic numbers . It is a tabular arrangement consisting of seven horizontal rows called periods and eighteen vertical columns called groups.
Elements present in the same group have same number of valence electrons and hence have similar properties while elements present in the same period show gradual variation in properties due to addition of one electron for each successive element in a period.
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What is the driving force for water to freeze below 0 degree C? what is the driving force for ice to melt above 0 degree C? ...?
Explanation:
When the water freezes, the variable which changes is the temperature because as we reduce the temperature, the particles will come closer to each other and the average kinetic energy of the particles of water decreases. Hence, the water freezes below 0°C.
In the case of melting, the temperature is increased which means that the particles move away from each other and the average kinetic energy of the particles of water at this temperature increases. Hence, the water melts above 100°C.
When applying heat to a substance changes the form, but not the identity of the substance, this is evidence of:
a chemical change
a physical change
no change
an anthropomorphic change
Answer:
This is the evidence of physical change.
Explanation:
When the substance is heated, its form is changed but identity remain the same, it is then a physical change. In physical change substance can only change their phases but not lose the identity. For example it may change its state from solid to liquid and liquid to gas.
Physical change:
The changes that occur only due to change in shape or form but their chemical or internal composition remain unchanged.
These changes were reversible.
They have same chemical property.
These changes can be observed with naked eye.
Example s:
Water converting to Ice .
Water converting to gas.
In this water molecule remain the same only they rearrange themselves that change its state of mater not composition.
Chemical change:
The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.
These changes are irreversible .
These changes occur due to chemical reactions .
These may not be observed with naked eye .
Examples:
combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood .
Boiling of egg: that change the chemical composition of protein in the egg
Derek needs a tool that delivers 25.00 mL of a sodium hydroxide solution. What tool would be best for him to use?
The best tool for Derek to use for delivering 25.00 mL of a sodium hydroxide solution is a volumetric pipette. Volumetric pipettes ensure precise volume measurements needed in laboratory settings.
To accurately measure and deliver 25.00 mL of a sodium hydroxide solution, the best tool for Derek to use is a volumetric pipette. Volumetric pipettes are specifically designed for precise volume measurements and are commonly used in laboratory settings to ensure accuracy.
Here’s a step-by-step guide on how Derek can use the volumetric pipette:
Rinse the volumetric pipette with the sodium hydroxide solution to ensure there is no contamination.Fill the pipette carefully with the sodium hydroxide solution up to the calibration mark.Dispense the solution into the desired container by allowing the liquid to drain out naturally without forcing it.By using a volumetric pipette, Derek can be confident that he has delivered exactly 25.00 mL of the sodium hydroxide solution, which is critical for accurate chemical preparations and reactions.
How many times does the digit 1 appear in the number 500, solution please
...?
How many moles is 15.8 cm3 of platinum? The density of platinum is 21.45 g/cm3.
The mass of platinum taken here is 338.9 g. The mass of one mole of platinum is 195 g. Then , number of moles in 338.9 g is 1.73.
What is platinum ?Platinum is 78th element in periodic table. It is a transition metal in d -block. Platinum is a precious metal used in making of ornaments, electrical devices etc.
volume Pt = 15.8 cm³
density = 21.4 g/ cm³
mass = volume × density = 338.9 g.
Atomic mass of platinum = 195 g/mol.
The mass of one mole of platinum metal is 195 g. Then the number of moles in 338.9 g can be calculated as follows:
no.of moles = weight/ atomic mass
n = 338.9 g / 195 g/mol
= 1.73 moles.
Therefore the number of moles of Pt is 1.73.
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Balance the equation, if necessary, for the reaction between iron and oxygen.
Fe + O₂ → Fe₂O₃
Answer:
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
Explanation:
The unbalanced reaction of the reaction between iron and oxygen is shown below as:-
[tex]Fe+O_2\rightarrow Fe_2O_3[/tex]
On the left hand side,
There is 1 iron atom and 2 oxygen atoms
On the right hand side,
There are 2 iron atoms and 3 oxygen atoms
Thus,
Right side, [tex]Fe_2O_3[/tex] is multiplied by 2.
Left side, [tex]O_2[/tex] must be multiplied by 3 and [tex]Fe[/tex] by 4 so to balance iron and oxygen.
Thus, the balanced reaction is:-
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
Which contributes to the dissolution of sugar in water?
a. the dissociation of an ionic compound in water
b. a strong pull of water molecules on an ionic compound
c. the dissociation of a polar covalent compound in water
d. a strong pull of water molecules on a polar covalent compound
Option C: The dissociation of a polar covalent compound in water.
Sugar is made up of sucrose molecules containing polar covalent bonds. They have same type of oxygen-hydrogen covalent bonds that are present in water.
Since, sugar is not an ionic compound, option a and option b are incorrect. Also, due to same type of bonding in water and sugar molecules there will be no such force of attraction between them, this will opt out the option d.
Thus, dissolution of sugar in water is the dissociation of a polar covalent compound in water and option c is correct.
Final answer:
The dissolution of sugar in water is due to the strong pull of water molecules on a polar covalent compound, like sugar, and is best explained by option d.
Explanation:
The dissolution of sugar in water is best described by option d, a strong pull of water molecules on a polar covalent compound. Sugar molecules are classified as polar covalent compounds because they contain regions of hydrogen-oxygen polar bonds. Due to the polarity of the water molecule, it can interact with these polar regions within sugar molecules through intermolecular forces. These interactions facilitate the separation of the sugar molecules into the solution, where they are surrounded by water molecules, leading to dissolution.
Water itself is a polar molecule, having a partial negative charge on the oxygen atom and a partial positive charge on the hydrogen atoms. Water molecules can surround the sugar molecules, aligning their charges with the opposite charges in the sugar molecule. This is what strongly pulls the sugar molecules apart and allows them to interact with more water molecules until they are evenly dispersed — thus the sugar is dissolved in the water due to the hydration process.
Calculate the number of atoms in 4.2 moles of sulfur atoms.
Now, calculate the mass of these same 4.2 moles.
Please show work! I have no clue how to solve this.
Final answer:
To calculate the number of atoms in 4.2 moles of sulfur atoms, use Avogadro's number. To calculate the mass of these 4.2 moles, multiply the number of moles by the molar mass of sulfur.
Explanation:
To calculate the number of atoms in 4.2 moles of sulfur atoms, you can use Avogadro's number. Avogadro's number is equal to 6.022 x 10^23 atoms per mole. So, by multiplying the number of moles (4.2) by Avogadro's number, you can determine the number of atoms:
Number of atoms = 4.2 moles * (6.022 x 10^23 atoms/mole) = 2.53 x 10^24 atoms.
To calculate the mass of 4.2 moles of sulfur atoms, you need to know the molar mass of sulfur. The molar mass of sulfur is 32.07 g/mol. Multiply the number of moles by the molar mass to find the mass:
Mass = 4.2 moles * 32.07 g/mol = 134.754 g.
If 4.00 moles of gasoline are burned, what volume of oxygen is needed if the pressure is 0.93 ATM, and the temperature is 35.0 degrees Celsius?
Which has a higher frequency, a neutron or electron? Why?
which of the following is a good scientific hypothesis
A. plants grow towards windows because the sun provides the food they need.
B. if sunlight causes skin cancer, the people should stay put of the sun.
C. plants that don't get sunlight will die.
D. if a plant is exposed to only blue light, the plant will grow more slowly
A testable, precise prediction of what you believe will occur in a scientific experiment that is based on your observations and past knowledge is called a scientific hypothesis. Here the correct option is D.
A scientific theory must satisfy two requirements in order to be accepted: it must be testable and falsifiable. A theory is not scientific if it cannot be verified through observation. A hypothesis is a rough explanation for a group of facts that can be put to the test by specific follow-up research.
Among the given options, if a plant is exposed to only blue light, the plant will grow more slowly can be proved by performing an experiment. Thus it is an example of a scientific hypothesis.
Thus the correct option is D.
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The atomic weight of hydrogen is
1?
The atomic weight of hydrogen is approximately 1 atomic mass unit. It is the lightest element with an atomic number of 1 and it consists mainly of one proton and one electron. The atomic weight represents the weighted average atomic mass of hydrogen's isotopes.
The atomic weight of hydrogen is often considered to be 1. This value is based on a standard atomic weight scale where hydrogen, the lightest element with the atomic number, Z, of 1, sets the reference point for the scale. The atomic mass of hydrogen is approximately 1 atomic mass unit (u), which is a unit derived from the mass of a carbon-12 atom. Since a hydrogen atom consists of one proton and one electron, and has no neutrons, its atomic mass is very close to 1 u. The actual mass of a hydrogen atom is about 1.7 x 10⁻²⁷ kg. However, in chemical reactions and on the periodic table, a weighted average of the atomic masses of the different isotopes of hydrogen (such as protium with no neutrons, deuterium with one neutron, and tritium with two neutrons) is used, leading to a slightly different average atomic mass of approximately 1.008. It is critical in chemistry to distinguish between the atomic number, which is the number of protons in the nucleus of an atom, and the atomic mass or atomic weight, which is the weighted average mass of an atom's isotopes as they occur naturally.
According to the periodic law, what is the relationship between elements and periods?
A. Elements have the same physical and chemical properties in any period.
B. Element properties repeat from period to period.
C. Elements in a period have the same physical properties.
D. Elements in a period have the same chemical properties.
Which statement defines the heat capacity of a sample? the temperature of a given sample the temperature that a given sample can withstand the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin) the quantity of heat that is required to raise 1 g of the sample by 1°C (or Kelvin) at a given pressure
Answer is: the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin).
Heat capacity of a sample is expressed in units of thermal energy per degree temperature (J/K).
Heat capacity is often defined relative to a unit of mass (J/kg·K or J/g·K), prefixed with the term specific.
For example, specific heat capacity of water is 4.184 J/g·K (Cp(H₂O) = 4.184 J/g·K).
The statement that defines the heat capacity of a sample is the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin).
WHAT IS HEAT CAPACITY?Heat capacity of a substance refers to the quantity of heat that is required to raise the temperature of the substance by 1°C or K.
The heat capacity of a substance can be measured in Jg/°C or JK/g.
The heat capacity of water molecule is 4.184 Jg/°C.
Therefore, the statement that defines the heat capacity of a sample is the quantity of heat that is required to raise the sample’s temperature by 1°C (or Kelvin).
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Which of the following statements is true about catalysts? and Why?
a. Catalysts slow down the rate of chemical reactions
b. All catalysts are enzymes
c. Catalysts are used up during a chemical reaction
d. Catalysts lower the activation energy of a chemical reaction
Your answer will be C. It's not D i just took the test
What is the layerof the sun in which energy is produced.?
You have two solutions of copper sulfate, one a deep blue and the other much paler. Is the first or second likely to be more concentrated? Is the first or
second likely to have higher absorbance
What is the name for the point at which the indicator changes color in a titration?
Answer:
End point.
Explanation:
The end point is the point at which the indicator changes color in a titration.
The end point generally lags behind the neutralization point in a reaction where we have taken acidic or basic indicator.
Indicators show a change or appearance in color at particular pH. This pH is achieved after point of neutralization. However for some indicators the change in color can also be observed at point of neutralization or completion of reaction exactly. In that case equivalence point and end point will coincide.
A large sac that stores water,salts and other materials for the cell is called a
Using the periodic table, which of the following elements has the most properties in common with calcium (Ca)?
scandium (Sc)
argon (Ar)
potassium (K)
magnesium (Mg)
atoms are made of 3 types of sub atomic particles; electrons, protons and neutrons
Of these particles, electrons are involved in the chemical reactions.
Therefore chemical properties of the element are determined by the electrons, and that too mostly the valence electrons. Valence electrons are the electrons in the outermost energy shell.
Atoms with same number of valence electrons have similar chemical properties. atoms having same number of valence electrons are classified into groups.
So elements of the same group have same number of valence electrons, hence similar chemical properties
Ca has 2 valence electrons so it belongs to group 2. Of the given elements
only Mg belongs to group 2. Therefore Mg has the most common properties with Ca
Where does a mid ocean ridge form?
Which of the following is likely to be a polar compound?
A. CHCl3
B. CCl4
C. CO2
D. CH4
Answer:
A) CHCl3
Explanation:
Polarity arises due to the difference in the electronegativity between two atoms forming a chemical bond. This difference also creates a dipole. A molecule is said to be polar if it has a net dipole moment. In symmteric molecules the dipole moments tend to cancel out making them non-polar.
A) CHCl3 is a tetrahedral molecule in which the central C atom is bonded to 3 Cl and 1 H atom. This molecule is not symmteric since there are 3 C-Cl and C-H bonds. Therefore, it will have a net dipole and will be polar
B) CCl4 is also a tetrahedral molecule, but symmetric in nature. Hence it will be non-polar
C) CO2 is a linear molecule where the dipole moments cancel out making it non-polar
C) CH4 is also a tetrahedral molecule and symmetric in nature. Hence it will be non-polar
A. CHCl₃ (chloroform) is the polar compound due to its tetrahedral structure with non-identical atoms and the resulting imbalance in electron distribution.
The compound likely to be a polar compound is CHCl₃. CHCl₃, or chloroform, is a polar molecule due to the uneven distribution of charge within its tetrahedral structure. Although the molecule has a tetrahedral geometry, the atoms bonded to the central carbon are not identical; there is one hydrogen and three chlorine atoms. Chlorine is more electronegative than carbon, and carbon is more electronegative than hydrogen, resulting in polar C-Cl bonds with a larger bond moment compared to the C-H bond. The difference in electronegativity and the arrangement of the atoms causes the bond dipole moments not to cancel out, yielding an overall dipole moment for the molecule. In contrast, molecules such as CCl₄ and CO₂ have symmetrical shapes and equal sharing of electrons, which result in nonpolar characteristics, while CH₄ also has a symmetrical tetrahedral structure with no significant differences in the electronegativity of the bonded atoms, rendering it nonpolar as well.
A gaseous hydrogen and carbon containing compound is decomposed and found to contain 82.66% carbon and 17.34% hydrogen by mass. The mass of 158 mL of the gas, measured at 556 mmHg and 25 ∘C, was found to be 0.275 g. What is the molecular formula of the compound?
To find the molecular formula of a compound, one must first determine the empirical formula based on mass percentages, calculate the molar mass using the ideal gas law, and then compare the empirical formula mass with the molar mass.
Explanation:To establish the molecular formula for the gaseous compound, we start by calculating its empirical formula using the percentages given: 82.66% carbon (C) and 17.34% hydrogen (H). With the assumption of a 100 g sample, we have 82.66 g of C and 17.34 g of H. Converting these masses to moles, we use the atomic mass of carbon (12.01 g/mol) and hydrogen (1.01 g/mol), yielding:
The empirical formula is obtained by dividing by the smaller number of moles:
Since we cannot have half a hydrogen in a formula, we multiply by 2 to get whole numbers, giving us an empirical formula of C2H5. Next, we calculate the molar mass (MM) using the provided conditions (158 mL at 556 mmHg and 25
C with a mass of 0.275 g). We apply the ideal gas law:
PV = nRT
Converting the pressure to atmospheres (556 mmHg / 760 mmHg/atm) and the volume to liters (158 mL / 1000 mL/L), and using the value of R (0.0821 Latm/molk), the molar mass can be calculated. Finally, comparing the empirical formula mass (EM) to the MM obtained allows for the determination of the molecular formula by finding the ratio between MM and EM, which tells us how many empirical units are in the molecular formula.
To summarize:
how many grams of mercury are present in a barometer that holds 6.5mL of mercury? ...?
Answer: The mass of mercury will be 20.15 g.
Explanation:
Density is defined as the mass contained per unit volume.
[tex]Density=\frac{mass}{Volume}[/tex]
Given : Mass of bromine = ?
Density of bromine= [tex]3.1g/ml[/tex]
volume of bromine = 6.5 ml
Putting in the values we get:
[tex]3.1g/ml=\frac{mass}{6.5ml}[/tex]
[tex]mass=20.15g[/tex]
Thus the mass of bromine is 20.15 g.
Which of these equations is balanced?
a. h2o co ---> h2co3
b. 2nacl h2so4 ----> na2so4 2hcl
c. 2cao h2o ----> ca(oh)2
d. mn fe ----> mns fe?
Pierce conducts an experiment in which waves collide in a way that the energy increases, which means that has occurred
It means the waves collides and constructive interference occurred.
Explanation:If the two waves coming from the opposite direction collide with each other, there are two way of their interference.
Constructive interference: An interference which results in the increase in energy. And it is when crust of a wave comes on the crust of second wave.Destructive interference: An interference which results in decrease in energy of the resulting wave and colliding waves cancel the result of each other.Hence in experiment there will be constructive interference.
Answer:
C.
Explanation:
I took the test!
A compound contains 69.94 percent iron and 30.06 percent oxygen. What is its molecular formula if the molar mass of the compound is 199.55 grams per mole?
Answer:
The molecular formula is Fe₂O₃
Explanation:
The molar mass of the compound is 199.55 g/mol; this means that if we have 1 mol of the compound, we'd have 199.55 g, we'd also have:
199.55 * 69.96/100 = 139.57 g of iron199.55 * 30.06/100 = 59.98 g of oxygenNow we calculate the moles of each element present in the given masses, using their atomic masses:
139.57 g Fe ÷ 55.84 g/mol = 2.50 mol Fe59.98 g O ÷ 16 g/mol = 3.75 mol OThen in 1 mol of the compound, there's 2.50 mol Fe and 3.75 mol O:
Fe₂.₅O₃.₇₅We convert the coefficients into integers (Divide them by the lowest number among them and multiply them by two):
Fe₂O₃what do gamma rays consists of?
A.only electrons
B.pure energy
C.only protons
D.beta particles
In the given question, Gamma rays consist of pure energy. The correct answer is option B.
Gamma rays are electromagnetic radiation with very high frequency and short wavelength.
They have no mass or charge, and are not considered particles like electrons, protons, or beta particles. Gamma rays are produced by the decay of atomic nuclei and are often associated with nuclear reactions such as those that occur in the sun, in nuclear power plants, or in nuclear weapons.
Therefore, Gamma rays are option B. "pure energy" in the form of electromagnetic radiation with an extremely high frequency and short wavelength.
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Water has a density of 0.997 g/cm^3 at 25 degrees C; ice has a density of 0.917 g/cm^3 at -10 degrees C. (question part a) If a soft drink bottle whose volume is 1.50L is completely filled with water and then frozen to -10 degrees C, what volume does the ice occupy? (question part b) Can the ice be contained within the bottle?
"The density of the water is given by the mass and the volume." The volume occupied by water is 1.63 L and ice cannot be contained in water as it has more volume.
What are volume and density?Volume has been inversely related to the density as increased volume decreases the density by their inverse relation. The division of the mass and volume gives the density of the substances.
Given,
Density of water = 0.997 g/cm³
Density of ice = 0.917 g/cm³
The volume of the soft drink bottle = 1.50 L
The volume of ice is calculated as:
Volume = mass ÷ density
V = 1495.5 ÷ 0.917
= 1630 cm³
The unit conversion is done as:
1 cm³ = 1 mL
1630 cm³ = 1630 mL = 1.630 L
Ice cannot be fitted into the soft drink bottles as the volume of ice 1.63 L is more than the volume of the bottle, 1.50 L.
Therefore, the volume of ice is 1.630 L.
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Which of the following elements is a metal?
carbon (C)
iodine (I)
iridium (Ir)
radon (Rn)
Iridium (Ir) is a element which is metal. Therefore, the correct option is option C among all the given options.
What is metal?Metal is any of a group of substances with strong thermal and electrical conductivity, malleability, ductility, as well as high light reflection. Typically, metals are crystalline solids. The free-electron hypothesis provides the best justification for the high thermal and electrical conductivity and high of the simple elements.
They typically have a very straightforward crystal structure that is characterized by dense atom packing and a high level of symmetry. Metal atoms often have fewer than half of their total number of electrons in the outermost shell. This property makes metals less likely to combine to create compounds. Iridium (Ir) is a element which is metal.
Therefore, the correct option is option C. Iridium (Ir) is a element which is metal.
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