Beta Decay

Q.

What are neutrons? What experimental evidence led us to assume the existence of neutrons?

Q. What is the respective number of $\alpha$ and $\beta$ particles emitted in the following radioactive decay ${}_{90}{X}^{200}{\to }_{80}{Y}^{168}$

1. 6 and 8
2. 8 and 8
3. 6 and 6
4. 8 and 6

Q.

If ${}_{92}{U}^{206}$ undergoes successively 8 $\alpha$ - decays and 6 $\beta$ - decays, then resulting nucleus is
[CBSE PMT 2002]

1. ${}_{82}{U}^{206}$

2. ${}_{92}P{b}^{206}$

3. ${}_{82}{U}^{210}$

4. ${}_{82}{U}^{214}$

Q. What happens in a ${\beta }^{+}$ (beta positive) decay?

1. Proton converts into a neutron.
2. Neutron converts into a proton.
3. Electron and antineutrino are created.
4. Positron and neutrino are created.

Q. Calculate the Q-value in the following decay:
${}_8^{19}O{\to }_9^{19}F+e^{-}+\overline{v}.$
These may look like long calculations; use the unit amu or u for the masses, and $c^2=931\frac{MeV}{u},$ and it will become much simpler.
$Atomicmasses{:}_8^{19}O:19.003576u;{}_9^{19}F:18.998403u.$

1. 2.021 MeV
2. 3.754 MeV
3. 4.816 MeV
4. 5.165 MeV

Q. Antineutrino particles are difficult to detect.

1. True
2. False

Q. Calculate the Q-value in the following decay:
${}_8^{19}O{\to }_9^{19}F+e^{-}+\overline{v}.$
These may look like long calculations; use the unit amu or u for the masses, and $c^2=931\frac{MeV}{u},$ and it will become much simpler.
$Atomicmasses{:}_8^{19}O:19.003576u;{}_9^{19}F:18.998403u.$

1. 2.021 MeV
2. 3.754 MeV
3. 4.816 MeV
4. 5.165 MeV

Q. An $\alpha -$particle of energy $3\text{MeV}$ is scattered through ${180}^{\circ }$ by gold nucleus. The distance of the closest approach is of the order of -

The atomic number of gold is $79$.

1. ${10}^{-11}\text{cm}$
2. ${10}^{-19}\text{cm}$
3. ${10}^{-13}\text{cm}$
4. ${10}^{-16}\text{cm}$

Q.

How was neutron discovered?

Q. If a Calcium atom with atomic number 20 and mass number 41 undergoes a ${\beta }^{-}$ (beta minus)
The value of Z is ___ and A is ___ in the daughter nucleus.

Q. Assuming that neon has an atomic radius of 70 pm. Calculate the mean free time for Neon at STP. (M for Neon = 20.18 g/mol)

Q. A free neutron can't undergo ${\beta }^{-}$decay in isolation.

1. False
2. True

Q. When ${}_{90}T{h}^{228}$ transforms to ${}_{83}B{i}^{212}$, then the number of the emitted $\alpha$ -and $\beta$ -particles is, respectively

1. $8\alpha ,7\beta$
2. $4\alpha ,7\beta$
3. $4\alpha ,4\beta$
4. $4\alpha ,1\beta$

Q. When a nucleus with atomic number $Z$ and mass number $A$ undergoes a radioactive decay process,

$\left(1\right)$ Both $Z$ and $A$ will decrease, if the process is $\alpha$ decay.
$\left(2\right)$ $Z$ will decrease, but $A$ will not change, if the process is ${\beta }^{+}$ decay.
$\left(3\right)$ $Z$ will increase, but $A$ will not change, if the process is ${\beta }^{-}$ decay.
$\left(4\right)$ $Z$ and $A$ will remain unchanged, if the process is $\gamma$ decay.

1. $1$ & $2$ are true
2. $1$, $2$ & $3$ are true
3. All are true
4. $3$ & $4$ are true