Q: What is the charge of a proton?

$$+1.60 \times 10$$^{-19}$$\ \mathrm{C}$$

Q: Which of the following is the correct definition of a mole?

The amount of substance containing $$6.022 \times 10$$^{23}$$ entities.

Q: If you have 2.45 mol of copper atoms, how many atoms do you have?

$$2.45 \times 6.022 \times 10$$^{23}$$ = 1.48 \times 10$$^{24}$$ atoms

Q: Which of the following is the correct formula for calculating atomic mass from isotopic abundances?

$$\text{Atomic mass} = \sum (x_i \times m_i)$$

Question 1

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting when exposed to oxygen.

Question 2

Which statement about the law of conservation of energy is correct?

Accepted Answer

Energy is transferred from one form to another, but the total amount remains constant.

Question 3

A sample of water contains 16.0 g of oxygen and 2.0 g of hydrogen. What is the mass ratio of oxygen to hydrogen in water?

Accepted Answer

$$\frac{16.0}{2.0} = 8.0$$

Question 4

Which of the following is a derived SI unit?

Accepted Answer

Meter per second squared ($$\mathrm{m/s^2$})$$

Question 5

Which of the following statements about isotopes is true?

Accepted Answer

Isotopes of an element have the same atomic number but different mass numbers.

Question 6

A student measures the mass of a sample three times and gets values very close to each other, but far from the actual mass. This demonstrates:

Accepted Answer

Low accuracy and high precision.

Question 7

Which scientist is credited with discovering the electron using the cathode ray tube experiment?

Accepted Answer

J.J. Thomson

Question 8

What is the charge of a proton?

Accepted Answer

$$+1.60 	imes 10$$^{-19}$$\ \mathrm{C}$$

Question 9

Which of the following is the correct definition of a mole?

Accepted Answer

The amount of substance containing $$6.022 	imes 10$$^{23}$$ entities.

Question 10

If you have 2.45 mol of copper atoms, how many atoms do you have?

Accepted Answer

$$2.45 	imes 6.022 	imes 10$$^{23}$$ = 1.48 	imes 10$$^{24}$$ atoms

Question 11

Which of the following elements is most likely to form a cation?

Accepted Answer

Sodium

Question 12

Which law states that all samples of a given compound have the same proportions of their constituent elements?

Accepted Answer

Law of Definite Proportions

Question 13

Which of the following is NOT a physical property?

Accepted Answer

Reactivity with oxygen

Question 14

Which of the following best describes the nucleus of an atom according to Rutherford's model?

Accepted Answer

It contains all the mass and positive charge.

Question 15

Which of the following is the correct formula for calculating atomic mass from isotopic abundances?

Accepted Answer

$$	ext{Atomic mass} = \sum (x_i 	imes m_i)$$

Question 16

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 17

Which of the following is a correct SI prefix for $$10^{-6}$$?

Accepted Answer

Micro

Question 18

A neutral atom of sodium has how many electrons?

Accepted Answer

11

Question 19

Which of the following is a chemical property?

Accepted Answer

Ability to react with chlorine

Question 20

Which of the following statements about ions is correct?

Accepted Answer

Cations have fewer electrons than the neutral atom.

Measurement, Physical and Chemical Change, and Energy in Chemistry

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