Hybrid cars get better gas mileage than cars with standard engines?

a) Always
b) Sometime
c) Daytime
d) Never

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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Final answer:

The oxidation number of Cl in the chlorate ion (ClO3-) is +5. This is determined by assigning oxygen an oxidation number of -2 and ensuring that the sum of oxidation numbers equals the ion's charge, which in this case is -1.

Explanation:

To determine the oxidation number of Cl in the chlorate ion (ClO3-), we apply the rules for assigning oxidation numbers. Here's how:

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

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).

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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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.

Electromagnetic waves can travel through a vacuum and do not require a medium. They include light, radio waves, and X-rays, among others.

The category of waves that cannot be seen and do not require a medium to travel through is known as electromagnetic waves. Unlike mechanical waves such as sound waves and water waves which need a medium (solid, liquid, or gas) to propagate, electromagnetic waves can travel through a vacuum. These consist of oscillations in electric and magnetic fields and include gamma rays, X-rays, ultraviolet waves, visible light, infrared waves, microwaves, and radio waves. A quintessential example of electromagnetic wave travel is visible light from distant stars reaching Earth through the vacuum of space.

Electromagnetic waves, including varieties like gamma rays and radio waves, do not require a medium to travel and can propagate through a vacuum at the speed of light.

The waves that cannot be seen and do not require a medium to travel through are known as electromagnetic waves. Unlike mechanical waves like sound and water waves, which require a medium such as air, water, or solids to travel through, electromagnetic waves can propagate through the vacuum of space. Some examples of electromagnetic waves include gamma rays, X-rays, ultraviolet waves, visible light, infrared waves, microwaves, and radio waves.

Electromagnetic waves are generated by the oscillations of electric and magnetic fields and they can move through a vacuum as they do not depend on a medium for their propagation. This characteristic allows electromagnetic waves to travel at a constant speed, known as the speed of light, which is approximately 2.99792458 × 108 m/s. Therefore, these waves are fundamentally different from mechanical waves, and this understanding is important for the study of physics and various applications in technology.

Answer:

True.

Explanation:

In 1824, the German chemist Johann Dobereiner, when analyzing the chemical elements calcium (Ca), strontium (Sr) and barium (Ba), noticed a simple relationship between their atomic masses: the mass of the strontium atom was very close to mass average of the other two elements. This observation was named the Triads of Chemical Elements and thus was born the law of the triads of Johann Döbereiner.

This law argued that elements with similar properties, ie, which reacted similarly with other elements, were organized in groups of three.

Your answer will be C. It's not D i just took the test

"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.

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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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.

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:

Final answer:

The chemical formula for fluorine in its standard state is F₂, which is a diatomic gas due to fluorine's high electronegativity.

Explanation:

The chemical formula for fluorine in its standard state is F₂. Fluorine is a diatomic molecule, meaning it naturally pairs up with another fluorine atom to form a molecule in its most stable and common form, denoted as F₂ gas. Rule 3 of assigning oxidation states is vital for fluorine due to its strong electronegativity, which is the highest among all elements. Thus, the F-F molecule can provide a reference point for calculating oxidation states of other elements.

Answer:

Osmium

Explanation:

Got it right on the test.

It means the waves collides and constructive interference occurred.

If the two waves coming from the opposite direction collide with each other, there are two way of their interference.

Hence in experiment there will be constructive interference.

Answer:

C.

Explanation:

I took the test!

What happens when  nitrogen fills its valence  shell is that 3 electron are gained  creating N3- ion

calculation

D.) Lose electrons when they form ions.

Final answer:

To find the oxidation numbers in Fe(NO3)2, we acknowledge that the sum is zero for a neutral compound. Each nitrate ion has an oxidation number of -1; thus, nitrogen is +5, and each oxygen is -2. Therefore, iron must have an oxidation number of +2 to balance the negative charge of the two nitrates.

Explanation:

To determine the oxidation numbers of elements in Fe(NO3)2, we follow the general rules for oxidation states. First, we know that the chemical compound as a whole is neutral, so the sum of all oxidation numbers in Fe(NO3)2 must be zero. Secondly, the oxidation number of oxygen is typically -2. In each nitrate ion (NO3−), there are three oxygen atoms contributing to a total of -6. The nitrate ion has a charge of -1, which means the nitrogen must have an oxidation number of +5 to balance the -6 from the oxygen atoms (x + 3(−2) = −1, x = +5).

Since there are two nitrate ions in Fe(NO3)2, this gives us a total negative charge of -2 from both nitrate ions. Consequently, the iron (Fe) must have an oxidation number of +2 to neutralize the charge from the nitrates (Fe2+). Thus, the complete set of oxidation numbers in Fe(NO3)2 is Fe2+ and two NO3− ions, with nitrogen being +5 and oxygen -2 in each nitrate ion.

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]

Answer : The number of moles of dipyrithione are [tex]1.4\times 10^1[/tex] moles.

Explanation :

The given molecule is, [tex]C_{10}H_8N_2O_2S_2[/tex]

In this molecule, there are 10 atoms of carbon, 8 atoms of hydrogen, 2 atoms of nitrogen, 2 atoms of oxygen and 2 atoms of sulfur.

As we know that, 1 mole of substance contains [tex]6.022\times 10^{23}[/tex] number of atoms.

As, [tex]6.022\times 10^{23}[/tex] atoms of [tex]N_2[/tex] present in 1 mole of [tex]C_{10}H_8N_2O_2S_2[/tex]

So, [tex]8.2\times 10^{24}[/tex] atoms of [tex]N_2[/tex] present in [tex]\frac{8.2\times 10^{24}}{6.022\times 10^{23}}=13.6\approx 1.4\times 10^1[/tex] mole of [tex]C_{10}H_8N_2O_2S_2[/tex]

Therefore, the number of moles of dipyrithione are [tex]1.4\times 10^1[/tex] moles.

There are 6.8 moles of dipyrithione that contain 8.2 x 10²⁴ atoms of N₂, calculated using Avogadro's number and the composition of the molecule.

Avogadro's number (NA) is 6.022 x 10²³ mol⁻¹, which is the number of particles in one mole of a substance. Since each molecule of N₂ contains two nitrogen atoms,  divide the total number of nitrogen atoms by two to find the number of N₂ molecules, and then divide by Avogadro's number to find the moles of N₂.

First, calculate the number of moles of N₂ by using the formula

[tex]n = \frac{N}{N_A}[/tex]

It relates the number of particles N to the number of moles n. In this case, N is the total number of nitrogen atoms given (8.2 x 10²⁴ atoms), which we divide by 2 to account for N₂, and then divide this number by Avogadro's number (6.022 x 10²³ mol-1) to find the moles of N₂:

nN2 = (8.2 x 10²⁴ atoms) / (2 x 6.022 x 10²³ mol⁻¹) = 6.8 moles of N₂

Since dipyrithione has one N₂ unit per molecule, the number of moles of dipyrithione is the same as the number of moles of N₂:

6.8 moles of dipyrithione will contain 8.2 x 10²⁴ atoms of N₂.

Answer:

A

Explanation:

This chemical reaction contains the elements carbon and oxygen.

The chemical symbol for the element carbon is C. The symbol for oxygen is O. Carbon dioxide (CO2) is a compound, not an element.

The given reaction C + O2 → CO2 contains the chemical elements carbon and oxygen. The reactant C represents carbon, while O2 represents oxygen as a diatomic molecule. The product CO2 represents carbon dioxide, which is composed of one carbon atom and two oxygen atoms.

In the given reaction C + O2 → CO2, the chemical elements involved are carbon and oxygen. The reactant C represents carbon, while O2 represents oxygen as a diatomic molecule. The product CO2 represents carbon dioxide, which is composed of one carbon atom and two oxygen atoms.

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

The modern periodic table arranges elements in order of increasing atomic number, which corresponds to the number of protons in an atom's nucleus. The increasing atomic number across the table helps predict properties and interactions of elements.

The modern periodic table is an essential tool in chemistry, used to catalog and organize the known elements. The table is arranged in order of increasing atomic number, which is equivalent to the number of protons in an atom's nucleus.

For instance, Hydrogen has an atomic number of 1 and is the first element on the table, while Helium has an atomic number of 2 and is the second element. As you move down and across the table, the atomic number continues to increase.

This help scientists to predict the properties of various elements, their reactivity, and how they might interact with other elements.

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In other words, the answer should be  

This can cause an explosion.  

posting this for future users to see!