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

How is percent yield calculated?

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

Какое вещество является основанием?

1. AСоляная кислота (HCl)
2. BУксус (уксусная кислота)
3. CЛимонный сок (лимонная кислота)
4. DГидроксид натрия (NaOH)

What is activation energy?

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

Rubbing alcohol evaporates faster than water at room temperature. What does this suggest?

1. AIt has a higher boiling point than water
2. BIts intermolecular forces are stronger than water's
3. CIts molecules are heavier than water molecules
4. DIts intermolecular forces are weaker than water's

Каково массовое содержание соли в процентах в растворе, приготовленном из 15 г соли и 135 г воды?

1. A10%
2. B11%
3. C15%
4. D90%

Which list is in order from smallest to largest mass?

1. AMilligram, gram, kilogram
2. BMilligram, kilogram, gram
3. CKilogram, gram, milligram
4. DGram, milligram, kilogram

Starch and cellulose are both made entirely of glucose units, yet humans can digest starch but not cellulose. Why?

1. ACellulose is really made of amino acids, not glucose, so stomach acid cannot break it
2. BThe glucose units are linked differently, and humans lack an enzyme to break cellulose's links
3. CStarch contains nitrogen, which makes it easier to digest
4. DCellulose dissolves in water, so it is lost from the gut

Why are the radioactive tracers used for medical imaging usually chosen to have short half-lives?

1. AShort half-life isotopes are not radioactive
2. BThey stay active for many years, so a single dose can be used for every future scan
3. CThey give a strong signal for imaging but leave the body's tissues exposed only briefly
4. DThey emit only alpha particles, which are harmless inside the body