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

What is a molecule?

1. AThe nucleus of an atom
2. BA mixture of two different elements
3. CTwo or more atoms held together by covalent bonds
4. DA single atom with a positive charge

How is percent yield calculated?

1. A(Mass of reactants ÷ mass of products) × 100
2. B(Theoretical yield ÷ actual yield) × 100
3. C(Actual yield ÷ theoretical yield) × 100
4. DActual yield − theoretical yield

What is activation energy?

1. AThe minimum energy reacting particles need for a reaction to happen
2. BThe energy needed to melt a solid
3. CThe energy stored in the products
4. DThe total energy released once the reaction has finished

Какова плотность тела массой 50 г и объёмом 20 см³?

1. A2,5 г/см³
2. B1000 г/см³
3. C70 г/см³
4. D0,4 г/см³

To which family of organic compounds does ethanol, C₂H₅OH, belong?

1. AAlcohols
2. BEsters
3. CCarboxylic acids
4. DAlkanes

How does electronegativity change going down a group?

1. AIt increases
2. BIt stays the same
3. CIt doubles with each period
4. DIt decreases

A strip of magnesium is burned in air and the white ash weighs more than the original strip. Why?

1. AOxygen from the air has combined with the magnesium
2. BThe ash absorbed water from the flame
3. CMass was created during the reaction
4. DMagnesium atoms became heavier when heated

A solution of a strong acid has pH 2. It is diluted with water to 10 times its original volume. What is the new pH?

1. A1
2. B20
3. C0,2
4. D3