C3B Quiz

What is the purpose of fluoridation of water?
1. To improve dental health
2. To make bones stronger.
3. To make teeth whiter
4. To get rod os excessive amounts of sodium fluoride
Pollution of water is a bad thing. Which one of these has the greatest impact on humans?
1. It smells offensive.
2. It looks offensive
3. Pollution can cause mutations in water animals.
4. It spreads disease.
Which one of these is true of hard water?
1. It has lots of sodium ions in it
2. It makes bones stronger
3. It has a pH of 10
4. The ions make soap easier to lather
In hard water areas, some people use water softeners. What do these do?
1. Replace carbonate ions with hydroxide ions.
2. Replace calcium ions with magnesium ions
3. Replace calcium ions with sodium ions
4. Replace sulphate ions with chloride ions.
Some hard water contains calcium hydrogencarbonate. Its hardness is:
1. slow
2. major
3. permanent
4. temporary
Which one of these correctly describes the solubility of substances with increasing temperature?
1. Solids become more soluble while gases become less soluble.
2. Solids become less soluble, while gases get more soluble.
3. Both liquids and gases become more soluble.
4. Both liquids and gases beome less soluble.
Which one of these liquids does NOT act as a solvent?
1. Paraffin
2. Petrol
3. Mercury
4. Water
Water is a good solvent because it is a polar molecule. What does this mean?
1. It has a north pole and a south pole
2. It has a slighlty negative region and a slightly positive region.
3. It dissociates into ions
4. It polarises light
Which one of these statements is true about an endothermic reaction?
1. It gives out heat
2. The energy needed to break bonds is less than the energy given out when the bonds reform.
3. The energy needed to break bonds is greater than the energy given out in forming the bonds
4. Adding a catalyst does not affect the reaction at all.
Fuels will not burn until a heat source is applied. This is because:
1. the reaction needs an activation energy to start
2. the reactions are endothermic
3. The heat acts as a catalyst.
4. More energy is needed to break the bonds than is got out by the reforming of the bonds
Which one of these statements is true for a catalyst?
1. It gets used up during the reaction
2. It increases the heat given out in an exothermic reaction
3. It increases the yield of the reaction
4. It lowers the activation energy for the reaction
1000 calories =
1. 1 J
2. 4.2 J
3. 1000 J
4. 4200 J
A sample of metal compound is burned in a flame. It gives a green flame. Which one of these is it most likely to be?
1. lithium
2. calcium
3. potassium
4. barium
A precipitate in chemistry is
1. a solid that will not dissolve in water
2. acid rain
3. a solid that results from the reaction of two solutions
4. a chemist's term for dropping an expensive piece of glassware on the floor.
In another test to identify a metal compound, a blue precipitate is seen. Which metal is it likely to be?
1. Copper
2. Iron
3. Silver
4. Magnesium
Which one of these is the correct test for nitrate ions?
1. Add some dilute hydrochloric acid then a few drops of barium sulphate.
2. Add some sodium hydroxide and aluminium powder. Test the gas with moist red litmus paper
3. Add nitric acid and observe the colour of the precipitate
4. React with hydrochloric acid. The gas given off turns limewater cloudy.
In another test on a sodium salt, a yellow precipitate is seen after adding some nitic acid. Which salt is this most likely to be?
1. fluoride
2. chloride
3. bromide
4. iodide
Which one of these hydrocarbons is impossible?
1. Methane
2. Methene
3. Ethane
4. Ethene
The emperical formula for ethene is:
1. CH2
2. CH4
3. C2H
4. C2H4
Another alkane has an empirical formula of CH4. What is its molecular formula?
1. CH4
2. C2H8
3. C3H12
4. C4H16