Q: Which of the following is the correct calculation for the atomic weight of an element with two isotopes: 70% of mass 35 and 30% of mass 37?

$$0.70 \times 35 + 0.30 \times 37$$

Question 1

Which of the following statements best describes an isotope?

Accepted Answer

Atoms with the same number of protons but different numbers of neutrons.

Question 2

A neutral atom of chlorine has an atomic number $$Z = 17$$ and a mass number $$A = 35. $$How many neutrons does it have?

Accepted Answer

$$18$$

Question 3

Which of the following ions is most likely to be formed by an element in Group 1A of the periodic table?

Accepted Answer

$$\mathrm{Na^+}$$

Question 4

Which of the following correctly represents the electron configuration for the oxide ion ($$\mathrm{O$$^{2-}$$}$$)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$

Question 5

Which of the following compounds is insoluble in water according to the solubility guidelines provided?

Accepted Answer

$$\mathrm{$$PbSO_4$$}$$

Question 6

What is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 7

Which of the following best describes a polar covalent bond?

Accepted Answer

A covalent bond between two atoms with different electronegativities.

Question 8

Which of the following molecules has a bent geometry and is polar?

Accepted Answer

$$\mathrm{H_2O}$$

Question 9

Given the following unbalanced equation: $$\mathrm{C_2H_6 + O_2$ \rightarrow CO_2$ + H_2O}$$, what are the correct coefficients to balance the equation?

Accepted Answer

$$2\ \mathrm{C_2H_6} + 7\ \mathrm{O_2$} \rightarrow 4\ \mathrm{CO_2$} + 6\ \mathrm{H_2O}$$

Question 10

Which of the following best explains why $$\mathrm{NaCl} is $$soluble in water but $$\mathrm{AgCl} is $$not?

Accepted Answer

$$\mathrm{Na^+}$$ and $$\mathrm{Cl^-}$$ ions are always soluble, but $$\mathrm{Ag^+}$$ forms an insoluble chloride.

Question 11

Which of the following elements has the highest electronegativity?

Accepted Answer

Fluorine

Question 12

What is the formula for the ionic compound formed between calcium and nitrate?

Accepted Answer

$$\mathrm{Ca(NO_3$)_2}$$

Question 13

Which of the following best describes the shape and bond angle of a molecule with four electron groups and two lone pairs on the central atom?

Accepted Answer

Bent, $$109^\circ$$

Question 14

Which of the following is a correct Lewis structure for $$\mathrm{CO_2$}$$?

Accepted Answer

O=C=O, with each O atom having two lone pairs

Question 15

Which of the following is the correct calculation for the atomic weight of an element with two isotopes: 70% of mass 35 and 30% of mass 37?

Accepted Answer

$$0.70 	imes 35 + 0.30 	imes 37$$

Question 16

Which of the following best describes a redox reaction?

Accepted Answer

A reaction in which electrons are transferred between species.

Question 17

Which of the following compounds will form a precipitate when mixed with a solution of $$\mathrm{Na_2SO_4}$$?

Accepted Answer

$$\mathrm{$$BaCl_2$$}$$

Question 18

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation has more protons than electrons, while an anion has more electrons than protons.

Question 19

Which of the following best explains why $$\mathrm{CO_2$} is a $$nonpolar molecule even though it contains polar bonds?

Accepted Answer

The molecule is linear, so the bond dipoles cancel each other out.

Atoms, Ions, and Chemical Reactions: Core Concepts and Solubility Guidelines

Guida di studio - Domande di pratica

Study guide - Flashcard