Law of Radioactivity

Q. 51. Calculate the mass of 2.5 gram atom of calcium?

Q. 2. the ratio of mass of an electrol to that of the mass of hydrogen atom is 1 1:3871 2 1:1837 3 1:1296 4 1:3781

Q. 4 g of a metal oxide contais 1.6 g oxygen, then equivalent mass of the metal is (1)3.2 (2)24 (3)12 (4)20

Q. Equivalent mass of the trivalent metal is 20.What will be the molar mass of its sulphate?

Q. If specific heat of a metal is 0.64cal g^-1 K^-1, then find the approximate and exact atomic mass of the metal assuming the equivalent mass of metal to be 2.75.

Q. 24. Eaplain law of isomorphism And from where the formula: Mass of one element (A) that combines with a certain mass of other element/mass of other element (B) that combine with the same mass of other element = atomic mass of A/atomic mass of B

Q. 43. the ratio of mass of calcium to oxygen in quick lime is(MCQ) 1. 4:1 2. 2:3 3. 5:2 4. 5:1

Q. 8. Chromium metal crystallises with a BCC lattice edge length is 287pm. Calculate the density of chromium in gm/cm . ( gram atomic weight of chromium is 52.2)

Q. Is charge Factor or size factor more dominant while determining polarising power of a cation?

Q. the chloride of solid metallic element contain 57.89% by mass of element.the specific heat of element is 0.0324cal/deg. calculate the exact mass of the element

Q. In a radioactive sample the decrease in the number of active nuclei at any time is directly proportional to?

1. Number of radioactive nuclei present in the starting
2. Time elapsed from the start time
3. Number of radioactive nuclei present at that particular instant
4. A small time interval from that particular instant.

Q.

1 amu when expressed as $1.66\times$ ${10}^{-x}$g , x =?

1. 20

2. 28

3. 24

4. 30

Q.

Two radioactive elements X and Y have decay constants$\lambda$ and $10\lambda$ respectively. If decay begins with the same number of atoms of them, the ratio of atoms of X to those of Y after time $\frac{1}{9\lambda }$ will be

1. $e$

2. $e^{-1}$

3. $e^2$

4. $e^{-2}$

Q. 4g of metal contains 1.6g of oxygen then equivalent mass of metal i

Q. 12 g of an alkaline earth metal gives 14.8 g of itsnitride. Atomic weight of the metal is

Q. FIND THE MASS OF 10 atoms OF Ag ?

Q. You have prepared a nice sample of $N_0$ radioactive nuclei of decay constant $\lambda$, and want to show it off to your friends. When they arrive units of time later, you open the lid and find there are only ___nuclei left intact.

1. $N_0{e}^{\lambda t}$
2. $N_0{e}^{-\lambda t}$
3. $N_0$
4. $N_0\lambda t$

Q. In presence of electric and magnetic field , where does the cathode rays deflect , towards positive or negatively charged particles ?

Q. 12 g of an alkaline earth metal gives 14.8 g of its hidride. Atomic weight of the metal is (1) 12 (2) 20 (3) 40 (4) 14.

Q. Amount of ${}_{53}{I}^{128}(t_{\frac{1}{2}}=25min)left$ after 75 minutes is

1. $\frac{1}{6}$
2. $\frac{1}{4}$
3. $\frac{1}{8}$
4. $\frac{1}{9}$

Q.

A freshly prepared radioactive source of half-life 2 hours emits radiations of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is

1. 6 hours
2. 12 hours
3. 24 hours
4. 128 hours

Q. Equal masses of two samples of charcoal A and B are burnt separately and the resulting carbon dioxide are collected in two vessels. The radioactivity of ${}^{14}C$ is measured for both the gas samples. The gas from the charcoal A gives 2100 counts per week and the gas from the charcoal B gives 1400 counts per week. Find the age difference between the two samples. Half-life of ${}^{14}C$ = 5730 y.

1. 2500 Years
2. 3352 Years
3. 4567 Years
4. 2392 Years

Q. The activity of a radioactive nuclide $\left(X^{100}\right)$ is $6.023$ curie at a certain time $‘t^{\prime }$. If its disintegration constant is $3.7\times {10}^4{s}^{-1}$ the mass of $X$ after t sec is:

1. $6.022\times {10}^{6}g$
2. ${10}^{-13}g$
3. ${10}^{-15}g$
4. ${10}^{-17}g$

Q. A sample of $U^{238}$ (half-life =$4.47\times {10}^9$ years) ore is found to contain 23.8 g of $U^{238}$ and 20.6 g of $P{b}^{206}$. Calculate the age of the ore in billion years.

Q.

If 12 g of sample is taken, and 6 g of a sample decays in 1 hr. The amount of sample showing decay in next hour is

1. 3 g
2. 1 g
3. 2 g
4. 6 g