answer is A
The kinetic theory is used to explain the behaviour of gases.
One of the assumptions states that "a gas is composed of a large number of identical molecules moving at different speeds".
The alkali metals are first column, alkali earth 2nd, halogens 2nd to last, and noble gases last. Hope it helps!
They work by lowering the activation energy
Answer : The ages of the brother and sister are, 10 and 16 years respectively.
Solution :
Let the age of brother be 'x' and the age of sister be 'y'
There are two equations formed which are,
x + y = 26 ..........(1)
3y - 4x = 8 ..........(2)
First we have to multiple equation (1) by 4 and then added equation (1) and (2), we get the value of 'y'.

Now put the value of 'y' in equation (2), we get the value of 'x'
3(16) - 4x = 8
4x = 40
x = 10
The age of brother = x = 10 years
The age of sister = y = 16 years
Therefore, the ages of the brother and sister are, 10 and 16 years respectively.
I got <span>0.00125 hm . Hope I helped, and good luck(: </span>