In the decay sequence: U 92 238 → - x 1 Th 90 234 → - x 2 Pa 91 234 → - x 3 Z 234 → - x 4 Th 90 234 x 1 , x 2 , x 3 and x 4 are the particles/ radiation emitted by the respective isotopes. The correct option(s) is/are:

x 1 will deflect towards the negatively charged plate.

To which series will the following elements belong? 257 103 Lr , 254 99 Es , 243 95 Am

Lr 103 257 : 257 is divisible by 4 , with remainder being 1 , hence, Lr 103 257 belongs to 4 n + 1 series. Es 99 254 : 254 is divisible by 4 , with remainder being 2 , hence, Es 99 254 belongs to 4 n + 2 series. Am 95 243 : 243 is divisible by 4 , with remainder being 3 , hence, Am 95 243 belongs to 4 n + 3 series.

10 . 0 gram-atom of an α - active radioisotope is disintegrating in a sealed container. In one hour, the He gas collected at STP is 11 . 2 litres. Calculate the half-life of the isotope supposing each nucleus yielding one He atom.

t = 1 hour Volume of He gas at STP = 11 . 2 litres ∴ Number of atoms obtained = 11 . 2 22 . 4 × 6 . 023 × 10 23 = 3 . 01 × 10 23 ∴ Disintegration per hour = 3 . 01 × 10 23 Disintegration per second = 3 . 01 × 10 23 3600 = 8 . 36 × 10 19 Number of atoms (given) = 10 × 6 . 023 × 10 23 = 6 . 023 × 10 24 ∴ A = λN 8 . 36 × 10 19 = λ × 6 . 023 × 10 24 λ = 8 . 36 6 . 023 × 10 - 5 = 1 . 38 × 10 - 5 S - 1 ∴ t 1 / 2 = 0 . 693 t 1 / 2 = 49920 . 86 sec t 1 / 2 = 49920 . 86 3600 hours = 13 . 86 hours

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STATEMENT-1: Specific activity of the same radioactive substance is same for 10g radioactive substance as well as 50g radioactive substance.

STATEMENT-2: Specific activity of a radioactive substance is its activity per g.

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Important Questions on Nuclear Chemistry

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

{}_{92}^{238}U

is known to undergo radioactive decay to form

{}_{82}^{206}{Pb}

by emitting alpha and beta particles. A rock initially contained

68 \times 10^{- 6} g

{}_{92}^{238}U

. If the number of alpha particles that it would emit during its radioactive decay of

{}_{92}^{238}U

{}_{82}^{206}{Pb}

in three half-lives is

Z \times 10^{18}

, then what is the value of

Z

MEDIUM

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

A nucleus

X

captures a

β

particle and then emits a neutron and

γ

ray to form

Y . X

and

Y

are:-

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

A radioactive sample is emitting

64

times radiations than non-hazardous limit. If its half life is

2 h

, after what time it become non hazardous?

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

In the nuclear transmutation

_{4}^{9} Be + X ⟶_{4}^{8} Be + Y

, identify

(X, Y)

EASY

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

Consider, the radioactive disintegration

{}_{82}A^{210} \to B \to C \to {}_{82}D^{206}

The sequence of emission can be

MEDIUM

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

A bacterial infection in an internal wound grows as

N^{'} (t) = N_{0} e x p (t)

, where the time

t

is in hours. A dose of antibiotic, taken orally, needs 1 hour to reach the wound. Once it reaches there, the bacterial population goes down as

\frac{d N}{d t} = - 5 N^{2}

. What will be the plot of

\frac{N_{0}}{N}

t

after

1

hour?

EASY

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

If the quantity of a radioactive element is doubled, the rate of disintegration will

MEDIUM

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

Predict the element resulting from two

α

decay, two consecutive

β

decay and one

γ

decay of

Th - 232

MEDIUM

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

In the decay sequence:

${}_{92}^{238}U \overset{- x_{1}}{\to} {}_{90}^{234}{Th} \overset{- x_{2}}{\to} {}_{91}^{234}{Pa} \overset{- x_{3}}{\to} {}^{234}Z \overset{- x_{4}}{\to} {}_{90}^{234}{Th}$

$x_{1}, x_{2}, x_{3}$ and $x_{4}$ are the particles/ radiation emitted by the respective isotopes. The correct option(s) is/are:

EASY

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

The decay constant which is the reciprocal of the time duration for which the number of the atoms of radioactive substance falls to

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

The ratio of the number of atoms of two radioactive elements $A$ and $B$ , in equilibrium with each other, is $3.1 \times 10^{9} : 1$ . If $t_{\frac{1}{2}}$ of element $B$ is $6.45$ years, calculate $t_{1 / 2} (Half - life)$ of element $A$ .

Give your answer up to one decimal place and if the answer is $X \times 10^{y}, give the value of X.$

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

To which series will the following elements belong?

$\begin{array}{l} 257 \\ 103 \end{array} Lr, \begin{matrix} 254 \\ 99 \end{matrix} Es, \begin{matrix} 243 \\ 95 \end{matrix} Am$

MEDIUM

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

5 g

of a radioactive substance has

t_{\frac{1}{2}} = 14 h, 20 g

of the same substance will have a

t_{\frac{1}{2}}

equal to

EASY

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

One becquerel of radioactivity is equal to

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

The disintegration rate for a sample containing

{}_{27}^{60}{Co}

as the only radioactive nuclide, is found to be

240

atoms/minute.

t_{\frac{1}{2}}

Co

5.2

years. Find the number of atoms of

Co

in the sample. How long(in years) must this radioactive sample be maintained before the rate falls to

100

disintegration per minute?

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

Calculate the number of disintegration which

1 g

{}^{226}{Ra} (t_{1 / 2} = 1600 years)

would undergo per second. What quantity of

{Na}^{24} (t_{1 / 2} = 15 hours)

would undergo the same number of disintegrations per second?

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

10.0

gram-atom of an

α -

active radioisotope is disintegrating in a sealed container. In one hour, the

He

gas collected at

STP

11.2

litres. Calculate the half-life of the isotope supposing each nucleus yielding one

He

atom.

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

The thorium radioactive decay series produces one atom of

{}^{208}{Pb}

as the final disintegration product of an atom of

{}^{232}{Th}

t_{\frac{1}{2}}

^{232} Th

1.39 \times 10^{10} years

. A certain rock is found to have a mass ratio of

{}^{208}{Pb}

and

{}^{232}{Th}

14 : 1

. Determine the age of the rock in multiple of

10^{10}

years.

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

A small quantity of solution containing ${Na}^{24}$ radionuclide of activity $1 microcurie$ is injected into the blood of a person. A sample of the blood of volume $1 {cm}^{3}$ taken after $5 hours$ shows an activity of $296 disintegration per minute$ . Assuming that the radioactive solution mixes uniformly in the blood of the person, what will be the total volume of blood in the body of the person?

(Take, $1 curie$ $= 3.7 \times 10^{10} disintegration per second$ and $e^{- λ t} = 0.7927$ , where, $λ =$ disintegration constant)

HARD

Chemistry>Physical Chemistry>Nuclear Chemistry>Applications of Radioactivity

One of the hazards of nuclear explosion is the generation of

{}^{90}{Sr}

and its subsequent incorporation in bones. This nuclide has a half-life of

28.1 year

. Suppose one microgram was absorbed by a new-born child, how much

{}^{90}{Sr}

will remain in his bones after

20 year

STATEMENT-1: Specific activity of the same radioactive substance is same for 10g radioactive substance as well as 50g radioactive substance.STATEMENT-2: Specific activity of a radioactive substance is its activity per g.

Important Questions on Nuclear Chemistry

Learn and Prepare for any exam you want !

STATEMENT-1: Specific activity of the same radioactive substance is same for 10g radioactive substance as well as 50g radioactive substance.

STATEMENT-2: Specific activity of a radioactive substance is its activity per g.