Airforce x group

An airforce plane is ascending vertically at the rate of 100km/h .If the radius of the earth is rkm, how fast is the area of the earth,visible from the plane,increasing at 3 minutes after it started ascending? Given that the visible area A at height h is given by A=2 pi r^(2)(h)/(r+h) .

If 30% of soldiers recruited in airforce in the year 2010 was female, what is the number of males recruited in airforce in that year?

Citric acid contains X carboxylic groups and Y hydroxy groups. Value of X+Y is

x=number of (+M) group attached with phenyl ring , so the value of x is .

identify the group 2 element 'X' in each of the following (i) The chemistry of X is quite different from that of other element in the group. (ii) 'X' forms organometallic compound RXBr. Which is very widely used?