Hannah does an experiment. She has two colorless chemicals that she mixes together in a beaker. Which of the following indicates that a chemical change occurs when she mixes the two chemicals together? I. The chemicals change color from colorless to purple. II. A yellow gas forms. III. A brown solid forms in the bottom of the beaker. IV. The temperature of the chemicals rises 15°C. A. II and III only B. I, II, III, and IV C. I and III only D. I, II, and III only

Answer:

Friedrich Wöhler (German: [ˈvøːlɐ]) FRS(For) HFRSE (31 July 1800 – 23 September 1882) was a German chemist, known for his work in inorganic chemistry, being the first to isolate the chemical elements beryllium and yttrium in pure metallic form.

Died: 23 September 1882

Born: 31 July 1800, Eschersheim, Germany

Nationality: Germany

Explanation:

Answer: The Atom would have:  

9 protons

19 electrons (since atoms are electrically neutral and have the same number of electrons as protons)

20 neutrons

Explanation: Hope this Helps.

To determine if a molecule is polar or nonpolar, follow these steps: draw the Lewis structure, figure out the molecular geometry, visualize or draw the geometry, and find the net dipole moment.

To determine if a molecule is polar or nonpolar, you need to follow a few steps:

In the case of CH3SH, the Lewis structure is H-C-H, with an S bonded to the central C atom. The geometry of the molecule is pyramidal, with the S atom at the top and the H atoms forming a triangular base. The S atom has higher electronegativity than the C and H atoms, so the S-H bond will be polar. Taking into account the molecular geometry, CH3SH is a polar molecule.

Actually we can see a lot of trends in the periodic table.

With regards to the atomic radius of the elements, going up to down there is an increasing pattern in the atomic radius.

While going left to right there is a decreasing pattern in the atomic radius.

Hence the smallest radius is on the upper right of the table.

Final answer:

Periodic trends in atomic radius indicate a decrease across a period due to increased nuclear charge pulling electrons closer, and an increase down a group due to the addition of electron shells. These trends result in the largest atoms being located in the lower left corner of the periodic table and the smallest in the upper right corner.

Explanation:

The question asks about the periodic trends in atomic radius. Atomic radius is a crucial concept in chemistry because it helps explain many properties of elements such as reactivity and bond length. Understanding these trends is fundamental for predicting and explaining chemical behavior.

Decrease Across a Period: Within a period, the atomic radius tends to decrease as the atomic number (Z) increases. This is because, across a period, electrons are added to the same energy level while the nucleus charges more positively, pulling electrons closer and resulting in a smaller atomic radius. For instance, going from potassium (K) to krypton (Kr), the radius decreases.

Increase Down a Group: Conversely, atomic radius increases as one moves down a group in the periodic table. This trend is due to the addition of electron shells as one moves to elements with higher atomic numbers, increasing the distance between the outer electrons and the nucleus. All alkali metals, for example, show an increase in atomic radius down the group.

In summary, atomic radii decrease from left to right across a row and increase from top to bottom down a column. Therefore, the largest atoms are found in the lower left corner of the periodic table, while the smallest are found in the upper right corner.

Answer: The density of cone is [tex]0.115g/cm^3[/tex]

Explanation:

The equation used to calculate the volume of cone is:

[tex]V=\frac{1}{3}\pi r^2h[/tex]

where,

V = volume of cone

r = radius of the cone = 5 cm

h = height of the cone = 2 cm

Putting values in above equation, we get:

[tex]V=\frac{1}{3}\times (3.14)\times (5)^2\times 2\\\\V=52.33cm^3[/tex]

To calculate volume of a substance, we use the equation:

[tex]\text{Density of a substance}=\frac{\text{Mass of a substance}}{\text{Volume of a substance}}[/tex]

We are given:

Mass of cone = 6 g

Volume of cone = [tex]52.33cm^3[/tex]

Putting values in above equation, we get:

[tex]\text{Density of cone}=\frac{6g}{52.33cm^3}\\\\\text{Density of cone}=0.115g/cm^3[/tex]

Hence, the density of cone is [tex]0.115g/cm^3[/tex]

The distinction between a strong acid (HClO₄) and a weak acid (HClO₂) lies in the extent of ionization in the solution. Strong acids ionize fully, while weak acids only partially ionize.

A strong acid is one that completely ionizes in water, while a weak acid only partially ionizes. The extent to which a substance is ionized in solution is determined by its dissociation constant (Ka).

HClO₄ is considered a strong acid because it fully dissociates into its ions when dissolved in water.

HClO₂ (chlorous acid),  is a weak acid. It only partially ionizes in water, meaning that only a fraction of the HClO₂ molecules dissociate into H+ and ClO⁻² ions. As a result, the concentration of H+ ions in the solution is lower compared to a strong acid like HClO₄, resulting in a weaker acidity.

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Answer:

Opinion

Explanation:

This is an opinion, actually. A Hypothesis has an "if/then" statement, for example, "IF I do not tie a knot at the end of a balloon THEN it will deflate". A scientific law states a fact that can be proven, such as Newtons Laws. A problem is the question you ask without making an educated guess.

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For us to accurately determine what compound this is, additional info must be given. However I can suggest two compounds which have molecular mass of about 30.07 g/mol.

1. It could be NO or nitric oxide.

The molecular mass is 16 + 14= 30 g/mol

But if we search the exact weight, it is 30.01 g/mol

2. It could also be (CH3)2  or ethane.

The molecular mass is 2*12+ 6*1= 30 g/mol

But if we search the exact weight, it is 30.07 g/mol.

So we could say it more likely to to be (CH3)2 

Answer:

C2H6

Explanation:

There is no central carbon atom therefore you can put subscripts on both atoms.

Final answer:

The nuclear symbol for the isotope with 26 protons and 30 neutrons is 56 Fe, and the hyphen notation is iron-56 or Fe-56. The element is iron (Fe).

Explanation:

The isotope in question has 26 protons and 30 neutrons. To find the nuclear symbol and the hyphen notation, we need to identify the element and calculate the mass number. This notation represents that the atom is an iron isotope with a mass number of 56 and an atomic number of 26 .

The element with 26 protons is iron (Fe).

The mass number (A) is the sum of the protons and neutrons, so A = 26 + 30 = 56.

Therefore, the nuclear symbol is 56 Fe, where 56 is the mass number and Fe is the symbol for iron.

The hyphen notation for this isotope is iron-56 or Fe-56.

To determine the number of moles of carbon monoxide present in the sample, use the Ideal Gas Law equation.

To determine the number of moles of carbon monoxide present in the sample, we can use the Ideal Gas Law equation, which is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.

First, convert the temperature from Celsius to Kelvin by adding 273.15. So, the temperature is 57°C + 273.15 = 330.15 K.

Now, rearrange the Ideal Gas Law equation to solve for n: n = PV / RT.

Substituting the given values into the equation, we have n = (67.88 kPa) * (85.3 L) / (0.0831 L·kPa/(mol·K)) * (330.15 K).

Simplifying the equation, we have n ≈ 231.36 moles of carbon monoxide in the sample.

To calculate the empirical formula from percent compositions, convert the percent composition of each element to grams, then to moles, and finally, divide the moles by the smallest number of moles obtained. In this case, the empirical formula is C5H7N.

The empirical formula can be calculated by finding the moles of each element in the compound using their percent compositions. In this case, we have 82% nitrogen, which corresponds to 82 grams, and 18% hydrogen, which corresponds to 18 grams. Next, we convert the grams to moles using the molar mass of each element. The molar mass of nitrogen (N) is 14 grams/mol, and the molar mass of hydrogen (H) is 1 gram/mol. Dividing the moles by the smallest number of moles obtained gives us the empirical formula. For this compound, the empirical formula is C5H7N.

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Answer:

The boron-11 should be more abundant

Explanation:

Atomic weight in the periodic table is an average value related to the percentaje of abundance of each isotope of the element.

Given that boron has only two isotopes (10 and 11), if their abundance would be 50%:

[tex]Ar=10*0.5+11*0.5=10.5[/tex]

Knowing that the boron's Ar is 10.81, we can afirm that boron-11 is more abundant.

Theoretically, boron atomicities of 10 and 11 are 10.5 on average. However, realistically speaking, boron has an atomic mass of 10.81 amu. Thus, it demonstrates that the average atomic mass of boron contains a higher abundance of boron-11. Atomic mass per unit, or amu, is a unit used to measure atomic mass.

If the abundance of boron-10 and boron-11 were equal, boron's atomic mass would be 10.5 amu. Therefore, the atomic mass of boron would be less than 10.5 amu if the percentage abundance of boron-10 is greater than the percentage abundance of boron-11.

In actuality, the atomic mass of boron is 10.81 amu rather than 10.5 amu, indicating that boron-11 has a higher proportion abundance than boron-10.

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There are two types of compound, covalent compound and ionic compound in chemistry, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Due to ease in movement of ions, melted ionic compound conduct electricity.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

Ionic compound are very hard. They have high melting and boiling point because of strong ion bond. When ionic compounds are in solid state the charged particles (ions) are not free to move but when in melted for, the ions are free to move. So, now they can conduct electricity.

Due to ease in movement of ions, melted ionic compound conduct electricity.

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A hypertonic solution has a higher osmolarity than a cell's cytoplasm, leading to water exiting the cell, known as crenation in red blood cells and plasmolysis in plant cells.

A hypertonic solution is one where the extracellular fluid has a higher osmolarity than the cytoplasm of a cell, causing water to move out of the cell. In such a solution, cells will lose water and shrink, which can be observed in red blood cells as crenation. Additionally, in plant cells, this phenomenon can result in the cell membrane detaching from the cell wall, known as plasmolysis.