Q: What is the formula mass of $$MgCl_2$$? (Atomic masses: Mg = 24.3, Cl = 35.5)

$$24.3 + 2 \times 35.5 = 95.3$$

Question 1

Which statement best describes the law of constant composition as it applies to water?

Accepted Answer

All samples of pure water contain hydrogen and oxygen in a fixed mass ratio.

Question 2

A sample of ammonia ($$NH_3) is $$decomposed and found to contain 14.0 g of nitrogen and 3.0 g of hydrogen. What is the mass ratio of nitrogen to hydrogen in ammonia?

Accepted Answer

$$\frac{14.0}{3.0} = 4.67$$

Question 3

Which of the following best distinguishes a compound from a mixture?

Accepted Answer

A compound contains elements in fixed, definite proportions.

Question 4

What is the empirical formula for hydrogen peroxide, whose molecular formula is $$H_2O_2$$?

Accepted Answer

$$HO$$

Question 5

How many oxygen atoms are present in one formula unit of $$Mg(NO_3$)_2$$?

Accepted Answer

6

Question 6

Which of the following is a molecular compound?

Accepted Answer

$$CO_2$$

Question 7

What is the correct name for the compound $$FeCl_3$$?

Accepted Answer

Iron(III) chloride

Question 8

Which of the following formulas represents an ionic compound?

Accepted Answer

$$Na_2SO_4$$

Question 9

What is the formula for the ionic compound formed between aluminum and oxygen?

Accepted Answer

$$Al_2O_3$$

Question 10

Which of the following is the correct name for $$KNO_3$$?

Accepted Answer

Potassium nitrate

Question 11

What is the formula mass of $$MgCl_2$$? (Atomic masses: Mg = 24.3, Cl = 35.5)

Accepted Answer

$$24.3 + 2 	imes 35.5 = 95.3$$

Question 12

Which of the following acids is correctly named?

Accepted Answer

$$HNO_3 is $$nitric acid

Question 13

Which of the following elements exists naturally as a diatomic molecule?

Accepted Answer

Chlorine

Question 14

What is the correct name for $$N_2O_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 15

Which of the following best describes the difference between $$CO$$ and $$CO_2$$?

Accepted Answer

They are different compounds with different properties due to different ratios of carbon and oxygen.

Question 16

Which of the following is the correct formula for calcium nitrate?

Accepted Answer

$$Ca(NO_3$)_2$$

Question 17

What is the correct name for $$H_2SO_3$$?

Accepted Answer

Sulfurous acid

Question 18

Which of the following is a polyatomic ion?

Accepted Answer

$$NO_3$$^-$$

Question 19

Which of the following is the correct name for $$CuSO_4$$?

Accepted Answer

Copper(II) sulfate

Question 20

A compound contains 12 carbon atoms, 22 hydrogen atoms, and 11 oxygen atoms per molecule. What is its molecular formula?

Accepted Answer

$$C_{12}H$$_{22}$$O_{11}$

Chapter 5: Molecules and Compounds - Structured Study Notes

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