A sample of radioactive element has a mass of 10 gm at an instant t = 0. The approximate mass of this element in the sample after two means lives in [CBSE PMT/PDT 2003]

1. 3.70 gm

2. 6.30 gm

3. 1.35 gm 

4. 2.50 gm

Given a sample of Radium-226 having half-life of 4 days. Find the probability, a nucleus disintegrates after 2 half lives [IIT-JEE 2006]

1. 1 

2. 1/2 

3. 1.5 

4. 3/4

Complete the equation for the following fission process-

$U_{92}^{235}+n_0^1\to S{r}_{38}^{90}+........$  

1. $X{e}_{{}_{54}}^{143}+3 n_0^1$ 

2. $X{e_{{}_{54}}^{145}}^{}$

3. $X{e_{{}_{57}}^{142}}^{}$ 

4. $X{e_{{}_{54}}^{142}}^{}+n_0^1$

A nucleus ruptures into two nuclear parts which have their velocity ratio equal to 2:1. What will be the ratio of their nuclear size (nuclear radius) ? 

1. $2^{1/3} : 1$ 

2. $1 : 2^{1/3}$ 

3. $3^{1/2} : 1$

4. $1 : 3^{1/2}$

The half-life of a radioactive material is 3h. If the initial amount is 300g, then after 18h, it will remain

1. 4.68 g 

2. 46.8 g

3. 9.375 g 

4. 93.75 g

Half-life of a radioactive substance is 20 min. Difference between points of time when it is 33% disintegrated and 67% disintegrated is approximately-

1. 10 min

2. 20 min 

3. 30 min

4. 40  min

When two deuterium nuclei fuse together to form a tritium nuclei, we get a

1. Neutron

2. Deutron

3. $\alpha$-particle

4. Proton

The most penetrating radiation out of the following is [1997]

1. $\gamma$-rays 

2. $\alpha$-particles

3. $\beta$-rays 

4. X-rays

In any fission process the ratio $\frac{mass of fission products}{mass of parent nucleus}$ is         [2005]

1. less than 1

2. greater  than 1

3. equal to 1

4. depends on the mass of parent nucleus

The nucleus ${}_{48}C{d}^{115}$, after two successive $\beta$-decay will give [1988]

1. ${}_{46}P{a}^{115}$   

2. ${}_{49}I{n}^{114}$

3. ${}_{50}S{n}^{113}$   

4. ${}_{50}S{n}^{115}$