(For a bit of context I will use the reaction between HCl and Mg as an example)
The larger the surface area of the magnesium metal, the more particles are exposed to collide with the aqueous HCl particles to cause the reaction to occur. This increases the frequency per second of collisions, speeding up the rate of reaction.
The effect of a catalyst is to reduce the minimum collision energy which allows the reaction to happen. This does not increase the number of collisions per second, but increases the percentage of successful collisions, which consequently causes the rate of reaction to increase .
I have drawn diagrams showing the effect of surface area, but there isn't really a meaningful diagram that I know of to show the impact of a catalyst (at least not at GCSE level).
C would be the correct answer
<span>1. In any nuclear reaction, nuclei are transformed in some way.
True
2. Two fissionable substances commonly used in nuclear reactors and nuclear weapons include uranium-235 and plutonium-239.
True
3. Fission reactions can be controlled; thus, they are used to create energy and electricity. But fusion reactions are uncontrollable and require too much energy for economical use.
True
4. Fission reactions occur at such high temperatures in the Sun that the Sun appears to glow.
False
Hope this answers the question. Have a nice day.</span>
Answer:We will use an acid to test whether sample contains calcium carbonate or not.
Explanation:
Calcium carbonate reacts with acids to give off carbon-dioxide gas ,water and calcium chloride. it is a salt of strong base calcium hydroxide and weak acid carbonic acid.

Evolution of carbon-dioxide on the reaction is also termed as effervescence.
If the sample contains the calcium carbonate strong effervesces will be observed and if not no effervescence will be observed.
We will use an acid to test whether sample contains calcium carbonate or not.