1) Carbon dioxide is a gas, so when
is evolved in the reaction, it appears as bubbles. The gas released extinguishes the fire and it can turn lime water milky.

2) When
is released in a decomposition reaction we can identify by the strong pungent smell of the gas released.
3) Saturated citric acid can cause corrosion of the metal layers present in the pipes. So, before draining out any acid it is neutralized so that the pipes and other plumbing works do not get damaged leading to leaks in the drainage system.
Answer:
the answer is D
Explanation:
percentage composition= mole of the substance divided by the total molar mass of the compound multiplied by 100.
Explanation:
<h3>Surface tension is the tendency of liquid surfaces to shrink into the minimum surface area possible. Surface tension allows insects, usually denser than water, to float and slide on a water surface.</h3>
Answer :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and the unpaired electrons present in the molecule.
The given molecule is, 
Beryllium has '2' valence electrons and fluorine has '7' valence electrons. Beryllium is the central atom and fluorine is the terminal atom.
Total number valence electrons in
= 2 + 2(7) = 16
According to the Lewis-dot structure, there are '4' number of bonding electrons and 12 number of non-bonding electrons (lone-pair).
The Lewis-dot structure is shown below.
It takes into account the different molecular masses of the different chemicals by providing a fixed and standardised number of molecules/ atoms for chemicals to be measured