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What is an empirical formula?

1. AThe simplest whole-number ratio of atoms in a compound
2. BA drawing of how the atoms are bonded
3. CThe actual number of each atom in one molecule
4. DThe mass of one mole of a compound

Which state of matter has a fixed volume but takes the shape of its container?

1. AGas
2. BPlasma
3. CLiquid
4. DSolid

Which of these is a heterogeneous mixture?

1. AAir
2. BSugar dissolved in tea
3. COil and water
4. DSalt dissolved in water

At 20 °C, about 36 g of NaCl dissolves in 100 g of water. If 50 g of NaCl is stirred into 100 g of water at 20 °C, what happens?

1. AAbout 36 g dissolves and about 14 g stays undissolved
2. BNone of the salt dissolves
3. CAll 50 g dissolves
4. DAbout 14 g dissolves and about 36 g stays undissolved

How does a mixture of iron filings and sulfur powder differ from the compound iron sulfide?

1. AThe mixture is formed by a chemical reaction between the two elements
2. BThe compound keeps the magnetic properties of iron
3. CThe mixture has a fixed ratio of iron to sulfur
4. DThe mixture can be separated physically, for example with a magnet

Why does the vapour pressure of a liquid increase as it is heated?

1. AMore molecules have enough energy to escape into the gas phase
2. BThe liquid's volume decreases and squeezes out vapour
3. CThe attractions between the molecules become stronger
4. DThe molecules become heavier and press harder on the surface

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

1. AAt low temperatures the reaction is too slow to be useful
2. BThe catalyst only works when the reaction is endothermic
3. CHigher temperatures shift the equilibrium toward more ammonia
4. DLow temperatures would make the ammonia explode

Ethanol (CH₃CH₂OH) and dimethyl ether (CH₃OCH₃) have the same formula, C₂H₆O, but ethanol boils at a much higher temperature. Why?

1. ADimethyl ether is ionic and ethanol is covalent
2. BEthanol has an O–H group, so its molecules form hydrogen bonds with each other
3. CEthanol molecules are heavier than dimethyl ether molecules
4. DEthanol has more carbon atoms