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

Which process is exothermic (releases heat)?

1. ABurning methane gas
2. BMelting a block of ice
3. CEvaporating water
4. DPhotosynthesis

How is percent yield calculated?

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

What is the change from a gas directly to a solid, skipping the liquid state, called?

1. ADeposition
2. BCondensation
3. CSublimation
4. DFreezing

What is carbon-14 dating used for?

1. ADetecting carbon monoxide in a room
2. BEstimating the age of material that was once alive
3. CFinding the exact age of rocks that are billions of years old
4. DMeasuring body temperature

What is nuclear fission?

1. AThe joining of two light nuclei to form a heavier nucleus
2. BThe burning of uranium in oxygen
3. CThe loss of electrons from an atom
4. DThe splitting of a heavy nucleus into smaller nuclei

Что такое водородные связи?

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

A salt is dissolved in water in an insulated cup, and the water temperature falls from 25 °C to 20 °C. Which statement is correct?

1. ANo energy change occurred, because the temperature fell
2. BDissolving is endothermic; the water took heat from the salt
3. CDissolving is endothermic; the dissolving salt took heat from the water
4. DDissolving is exothermic; the dissolving salt released heat into the water

pH раствора изменился с 6 до 4. Что произошло с концентрацией ионов водорода?

1. AОна стала в 100 раз больше
2. BОна стала в 2 раза меньше
3. CОна стала в 100 раз меньше
4. DОна стала в 2 раза больше