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

What does the subscript 2 in H₂O tell you?

1. AThere are two water molecules
2. BEach molecule contains two hydrogen atoms
3. CEach molecule contains two oxygen atoms
4. DWater has a charge of 2

What is a single covalent bond?

1. AOne electron transferred from one atom to another
2. BTwo pairs of electrons shared between two atoms
3. CThe attraction between two oppositely charged ions
4. DOne pair of electrons shared between two atoms

Какой тип реакции показан в реакции A + B → AB?

1. AРазложение
2. BГорение
3. CЗамещение
4. DСоединение (синтез)

Что такое водородные связи?

1. AСвязи внутри ядра водорода
2. BИонные связи между ионами водорода и металлами
3. CКовалентные связи между двумя атомами водорода в H₂
4. DПритяжение между водородом одной молекулы и атомом O, N или F другой

A red blood cell is placed in a concentrated (hypertonic) salt solution. What happens?

1. AWater enters the cell, which swells and may burst
2. BWater leaves the cell, which shrinks
3. CSalt leaves the cell, which swells
4. DThe cell stays the same size and shape

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

A piece of copper is placed in zinc sulfate solution. Zinc is more reactive than copper. What happens?

1. ANo reaction occurs
2. BHydrogen gas is produced
3. CZinc metal coats the copper and the solution turns blue
4. DCopper replaces zinc, forming copper sulfate

A catalyst is added to an exothermic reaction. How does the energy diagram change?

1. AThe peak is lower, but the energy of reactants and products stays the same
2. BThe reaction becomes endothermic
3. CThe products end up at a lower energy, so more heat is released
4. DThe reactants start at a higher energy