The half-life period of a radioactive substance is 6 h.  After 24 h activity is 0.01 $\mu$Ci, what was the initial activity? 

(1) 0.04 $\mu$Ci         (2) 0.08 $\mu$Ci           (3) 0.24 $\mu$Ci              (4) 0.16 $\mu$Ci

The relationship between disintegration constant $\left[\lambda \right]$ and half-life [T] will be:

(1) $\lambda =\frac{{\log }_{10} 2}{T}$                    (2) $\lambda =\frac{{\log }_e 2}{T}$

(3) $\lambda =\frac{T}{{\log }_e 2}$                      (4) $\lambda =\frac{{\log }_2 e}{T}$

If the nuclear force between two protons, two neutrons and between proton and neutron is denoted by $F_{pp}, F_{nn} and F_{pn}$ respectively, then [1991]

(1) $F_{pp}\approx F_{nn}\approx F_{pn}$

(2) $F_{pp}\ne F_{nn} and F_{pp}=F_{nn}$

(3) $F_{pp}=F_{nn}=F_{pn}$

(4) $F_{pp}\ne F_{nn}\ne F_{pn}$

In a given reaction,

${}_{Z}X_A\to {}_{Z+1}Y_A\to {}_{Z-1}K_{A-4}\to {}_{Z-1}K_{A-4}$

Radioactive radiations are emitted in the sequence of  

(1)  $\alpha , \beta , \gamma$       (2) $\gamma , \alpha , \beta$             (3) $\beta , \alpha , \gamma$            (4) $\gamma , \beta , \alpha$

If a proton and anti-proton come close to each other and annihilate, how much energy will be released?

Heavy water is used as a moderator in a nuclear reactor. The function of the moderator is 

(1) to control energy released in the reactor

(2) to absorb neutrons and stop the chain reaction

(3) to cool the reactor

(4) to slow down the neutrons to thermal energies

The binding energy per nucleon of deuterium and helium atom is 1.1 MeV and 7.0 MeV. If two deuterium nuclei fuse to form a helium atom, the energy released is 

(1) 19.2 MeV            (2) 23.6 MeV             (3) 26.9 MeV                (4) 13.9 MeV

In a fission reaction,

${}_{92}{}^{236}U\to {}_{117}X+{}_{117}Y+n+n$

the binding energy per nucleon of X and Y is 8.5 MeV whereas of ${}_{236}U$ is 7.6 MeV. The total energy liberated will be about [1997]

(1) 2000 MeV          (2) 200 MeV               (3) 2 MeV            (4) 1 keV

A nuclear decay is expressed as 

${}_{6}C_{11}\to {}_{5}B_{11}+{\beta }^{+}+X$

Then the unknown particle X is:

(1) Neutron          (2) antineutrino             (3) proton               (4) neutrino

The rate of disintegration of a fixed quantity of a radioactive substance can be increased by

(1) increasing the temperature

(2) increasing the pressure

(3) chemical reaction

(4) it is not possible