Užduočių lapas tema Chemija slaugos stojamiesiems egzaminams su atsakymais

Where do the mole ratios used in stoichiometry come from?

1. AThe coefficients of the balanced equation
2. BThe subscripts in each formula
3. CThe molar masses of the reactants
4. DThe physical states of the substances

What is an acid–base indicator?

1. AA substance that neutralises every acid
2. BA substance that changes colour depending on pH
3. CA gas given off by acids
4. DA device that measures temperature

How does increasing the concentration of a reactant in solution usually affect the reaction rate?

1. AThe rate decreases
2. BThe reaction stops
3. CThe rate stays the same
4. DThe rate increases

Einant periodu iš kairės į dešinę, kaip paprastai keičiasi atomo spindulys?

1. APirmiausia padvigubėja, paskui perpus sumažėja
2. BMažėja
3. CLieka lygiai toks pat
4. DDidėja

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 floats
3. CIt dissolves
4. DIt sinks

What is the name of the molecular compound CO?

1. ACarbon oxide
2. BCarbon dioxide
3. CCarbon monoxide
4. DMonocarbon oxide

Making ammonia (N₂ + 3H₂ ⇌ 2NH₃) is exothermic. A low temperature would give a higher yield, yet factories use a moderately high temperature. Why?

1. ALow temperatures would make the ammonia explode
2. BHigher temperatures shift the equilibrium toward more ammonia
3. CThe catalyst only works when the reaction is endothermic
4. DAt low temperatures the reaction is too slow to be useful

Why is it easier to remove the outer electron from a potassium atom than from a lithium atom?

1. ALithium has more electron shells than potassium
2. BPotassium's outer electron is in a full shell
3. CPotassium's outer electron is farther from the nucleus and more shielded by inner electrons
4. DPotassium has fewer protons, so its nucleus pulls much more weakly on every electron