Химия для вступительных экзаменов на сестринские программы: лист заданий с ответами

What is a cation?

1. AA negatively charged ion
2. BA positively charged ion
3. CA molecule with no charge
4. DA neutral atom

Which is a sign that a chemical reaction may have taken place?

1. AA gas is produced when two liquids are mixed
2. BSugar dissolves completely when stirred into water
3. CWater freezes into ice when put in a freezer
4. DA block of wax melts when it is heated

What is the melting point of a substance?

1. AThe temperature at which its solid turns into a liquid
2. BThe temperature at which it dissolves in water
3. CThe temperature at which it catches fire
4. DThe temperature at which its liquid turns into a gas

What is the formula of sodium sulfate, made from Na⁺ and SO₄²⁻ ions?

1. ANa(SO₄)₂
2. BNa₄SO₂
3. CNaSO₄
4. DNa₂SO₄

Which type of radiation can be stopped by a sheet of paper?

1. AGamma rays
2. BX-rays
3. CAlpha particles
4. DBeta particles (fast electrons)

A plastic block has a density of 0,8 g/cm³. What happens when it is placed in water (density 1,0 g/cm³)?

1. AIt floats
2. BIt sinks
3. CIt stays suspended halfway down
4. DIt dissolves

At room temperature chlorine (Cl₂) is a gas, bromine (Br₂) is a liquid and iodine (I₂) is a solid. What best explains this trend?

1. AIodine forms hydrogen bonds but chlorine does not
2. BLarger molecules with more electrons have stronger dispersion forces
3. CChlorine is ionic, while iodine is metallic
4. DThe covalent bond in I₂ is much stronger than in Cl₂

Which pair of substances could form a buffer solution?

1. AHydrochloric acid (HCl) and chloride (Cl⁻)
2. BCarbonic acid (H₂CO₃) and bicarbonate (HCO₃⁻)
3. CHydrochloric acid (HCl) and sodium hydroxide (NaOH)
4. DSodium chloride (NaCl) and water