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

According to the Arrhenius definition, what does an acid produce in water?

1. AOxide ions (O²⁻)
2. BHydroxide ions (OH⁻)
3. CHydrogen ions (H⁺)
4. DSodium ions (Na⁺)

What is the change from a liquid to a solid called?

1. AMelting
2. BEvaporation
3. CCondensation
4. DFreezing

What is an unsaturated solution?

1. AA solution with undissolved solid at the bottom
2. BA solution that can still dissolve more solute
3. CA solution with no solute at all
4. DA solution that holds the maximum possible solute

How many lone (non-bonding) pairs of electrons are on the oxygen atom in a water molecule?

1. A2
2. B1
3. C0
4. D4

How many covalent bonds does a carbon atom usually form?

1. A1
2. B4
3. C2
4. D3

What is the oxidation number of oxygen in most of its compounds?

1. A−1
2. B+2
3. C0
4. D−2

Which compound contains both ionic and covalent bonds?

1. AWater, H₂O
2. BSodium sulfate, Na₂SO₄
3. CSodium chloride, NaCl
4. DMethane, CH₄

CO₂ in blood forms carbonic acid: CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻. An anxious patient hyperventilates and breathes off extra CO₂. What happens to blood pH?

1. AIt stays exactly 7,40, because CO₂ does not affect pH
2. BIt falls, because oxygen is an acid
3. CIt rises, because less CO₂ means fewer H⁺ ions
4. DIt falls, because less CO₂ means more H⁺ ions