Radius ratio corresponding to first, second and third orbit in `H-` atom, `r1: r2: r3` is `a) 1:1:1` `b) 1:4:9` `c) 1:2:3` `d) 1:9:8`

If the ratio of the areas of two square is 9:1, then the ratio of their perimeters is (a) 2:1 (b) 3:1 (c) 3:2 (d) 4:1

Let omega be a complex cube root unity with omega != 1. A fair die is thrown three times. If r_1,r_2 and r_3 are the numbers obtained on the die, then the probability that omega^(r1) + omega^(r2) + omega^(r3)=0 is (a) 1/18 (b) 1/9 (c) 2/9 (d) 1/36

If R_1 is the radius of the first of hydrogen atom then the radii of second , third and fourth orbitals in term of r_1 are

If the radius of first, second, third and fourth orbit of hydrogen atom are r_(1),r_(2),r_(3) and r_(4) respectively .Then their correct increasing order will be:

The height and radius of the cone of which the frustum is a part are h_1 and r_1 respectively. If h_2 and r_2 are the heights and radius of the smaller base of the frustum respectively and h_2\ : h_1=1\ :2 , then r_2\ : r_1 is equal to (a) 1\ :3 (b) 1\ :2 (c) 2\ :1 (d) 3\ :1

Calculate the ratio of the radius of 1^(st) orbit of H atom to thatof 4^(th) orbit. Hint : r_(n) prop ( n)^(2)

Calculate the ratio of the radius of 1^(st) orbit of H atom to that of 4^(th) orbit. Hint : r_(n) prop ( n)^(2)

In the situation shown, resistance R_(1),R_(2) and R_(3) are in the ratio 3:2:1 , then

In any triangle, the minimum value of r_1r_2r_3//r^3 is equal to (a) 1 (b) 9 (c) 27 (d) none of these

Two moles of oxygen are mixed with eight moles of helium. The effective specific heat of the mixture at constant volume is a) 1.3 R b) 1.4 R c) 1.7 R d) 1.9 R