in which state of matter are particles packed tightly together in a fixed position

HESI A2

HESI A2 Chemistry Questions

1. In which state of matter are particles packed tightly together in a fixed position?

A. Liquid
B. Solid
C. Gas
D. Plasma

Correct answer: B

Rationale: In a 'solid' state, particles are tightly packed in fixed positions, maintaining a definite shape and volume. This arrangement allows solids to maintain a rigid structure. Liquids have particles that are close together but can move past each other, giving them the ability to flow and take the shape of their container. Gases have particles that are far apart and move freely, leading to their ability to expand to fill any container. Plasma is an ionized gas where particles have high energy levels and are not packed tightly together, making it an uncommon state of matter on Earth.

2. In the solid state, you would expect a nonmetal to be _________.

A. brittle
B. lustrous
C. malleable
D. conductive

Correct answer: A

Rationale: In the solid state, you would expect a nonmetal to be brittle. Nonmetals generally lack the malleability and ductility of metals, which makes them prone to being brittle and easily fractured under stress. This property is due to the lack of metallic bonding in nonmetals, which results in a more rigid and less flexible structure. Choice B, 'lustrous,' is incorrect because nonmetals typically do not exhibit a shiny or reflective surface like metals do. Choice C, 'malleable,' is also incorrect as nonmetals lack the ability to be hammered or rolled into thin sheets like metals. Choice D, 'conductive,' is incorrect since nonmetals are generally poor conductors of electricity compared to metals.

3. What does the mass of one mole of a substance represent?

A. Atomic mass
B. Mass number
C. Molecular weight
D. Molar mass

Correct answer: D

Rationale: The mass of one mole of a substance is represented by its molar mass. Molar mass is the mass of one mole of a substance and is expressed in grams per mole. It is calculated by summing the atomic masses of all atoms in a molecule. Therefore, the correct answer is D - 'Molar mass'. Choice A, 'Atomic mass', refers to the average mass of an atom of an element. Choice B, 'Mass number', is the total number of protons and neutrons in an atom's nucleus. Choice C, 'Molecular weight', is the average mass of a molecule relative to 1/12 of the mass of an atom of carbon-12.

4. What does a blood sample with a pH of 3 indicate?

A. It is strongly acidic.
B. It is strongly basic.
C. It is weakly acidic.
D. It is weakly basic.

Correct answer: A

Rationale: A blood pH of 3 is significantly low, indicating a strong acidity level. The normal blood pH range is 7.35 to 7.45; therefore, a pH of 3 is far below the normal range, showing a highly acidic condition in the blood sample. Choice B is incorrect because a pH of 3 is not basic at all. Choice C is incorrect as a pH of 3 is not weakly acidic but strongly acidic. Choice D is wrong as a blood pH of 3 does not indicate a weakly basic condition.

5. Which two elements are most alike in reactivity?

A. He and H
B. K and Ar
C. Cl and P
D. Ba and Mg

Correct answer: C

Rationale: Chlorine (Cl) and Phosphorus (P) are most alike in reactivity among the given pairs. Both elements are nonmetals and belong to Group 7 (halogens) and Group 15 (nitrogen group), respectively. They have similar electronic configurations and can form compounds by gaining or sharing electrons. Chlorine is highly reactive and can easily form ionic compounds, while phosphorus also shows a range of reactivity in its compounds. Choice A (He and H) is incorrect because helium (He) is a noble gas and hydrogen (H) is a nonmetal, so they are not similar in reactivity. Choice B (K and Ar) is incorrect as potassium (K) is a metal and argon (Ar) is a noble gas, having different reactivities. Choice D (Ba and Mg) is incorrect because barium (Ba) and magnesium (Mg) are both metals, but their reactivities differ due to their positions in the periodic table.