Isotopes

Q.

The weight of silver displaced by a quantity of electricity which displaces 5600 ml of O₂ at STP will be

1. 5.4 g

2. 108.0 g

3. 54.0 g

4. 10.8 g

Q.

What do you mean by B.E.C.?

Q.

Calculate the average atomic mass of the bromine atom.

Q.

The radioactive isotope used in the treatment of cancer is:

(a) plutonium-239

(b) arsenic-74

(c) cobalt - 60

(d) iodine-131

Q.

Which of the following element is used in the treatment of cancer?

1. Iodine

2. Uranium

3. Cobalt

4. Nickel

Q.

Chlorine is an element of atomic number 17. It is a mixture of two isotopes having mass number of 35 and 37.

State the number of protons, electrons and neutrons in the following isotopes: ${{}^{35}\mathrm{Cl}}_{17}$, ${{}^{37}\mathrm{Cl}}_{17}$ .

Q.

Question 8(c)
Convert into mole:
(c) 22 g of carbon dioxide

Q.

(a) What are radioactive isotopes ? Give two examples of radioactive isotopes.

(b) Give any two uses of radioactive isotopes.

(c) An element Z contains two naturally occurring isotopes ${}_{17}^{35}Zand{}_{17}^{37}Z$. If the average atomic mass of this element be 35.5 u, calculate the percentage of two isotopes.

Q.

The isotopes of an element contain :

(a) same number of neutrons but different number of protons

(b) same number of neutrons but different number of electrons

(c) different number of protons as well as different number of neutrons

(d) different number of neutrons but same number of protons

Q. Question 19
Is it possible for the atom of an element to have one electron, one proton and no neutron? If so, name the element.

Q.

${}_{12}^{24}Mgand{}_{12}^{26}Mg$ are symbols of two isotopes of magnesium.

(a) Compare the atoms of these isotopes with respect to :

(i) the composition of their nuclei.

(ii) their electronic configurations.

(b) Give reasons why teh two isotopes of magnesium ahve different mass numbers.

Q.

What are the similarities and dissimilarities be­tween isotopes of same species? Give example with reasons.

Q.

Magnesium is two times heavier than C-12 atom, what shall be the mass of Mg atom in terms of atomic mass unit?

1. 24u

2. 22u

3. 18u

4. 20u

Q.

An element X occurs in nature in three isotopic forms with masses 30u, 32u and 33 u in the ratio 3:3:4. What is the average mass of element X?

1. 33.20

2. 30.10

3. 32.10

4. 31.80

Q.

Explain why the atomic masses of many ele­ments are in fractions and not in whole numbers ?

Q.

Question 13
Composition of the nuclei of two atomic species, X and Y are given as under
X Y
Protons = 6 6
Neutrons = 6 8
Give the mass numbers of X and Y. What is the relation between the two species?

Q.

Two elements having same number of protons and electrons but different number of neutrons

Q. Question 7(b)
What is the mass of:
(b) 4 moles of aluminium atoms (atomic mass of aluminium = 27)?

Q.

Which of the following are characteristics of isotopes of an element?
(i) Isotopes of an element have the same atomic masses.
(ii) Isotopes of an element have the same atomic number.
(iii) Isotopes of an element show the same physical properties.
(iv) Isotopes of an element show the same chemical properties.

1. (i), (iii) and (iv)

2. (ii) , (iii) and (iv)

3. (ii) and (iii)

4. (ii) and (iv)

Q.

State one use of radioactive isotopes in medicine.

Q.

Which of the following gases do not have neutron in the nucleus of their atoms?

1. Nitrogen

2. Oxygen

3. Hydrogen

4. Helium

Q.

Which of the following pairs are isotopes? Give reasons for your choice:

(i) ${}_{26}^{58}A$, ${}_{28}^{58}B$ or (ii) ${}_{35}^{79}X$, ${}_{35}^{80}Y$

Q.

Terrestrial hydrogen contains deuterium mostly in the form of _______.

Q.

Why do Isotopes have similar chemical properties ?

Q.

Why do ${}_{17}^{35}Cland{}_{17}^{37}Cl$ have the same chemical properties ? In what respect do these atoms differ ?

Q.

Isotopes have different mass numbers because their nuclei contain different number of__.

Q.

Hydrogen has three isotopes written as: ${}_1^{1}H,{}_1^{2}H,{}_1^{3}H$

Explain why:

(i) these isotopes have almost identical chemical properties.

(ii) they are electrically neutral.

Q.

What is the reason for the identical chemical properties of all the isotopes of an element ? Explain with the help of an example.

Q.

What is the reason for the slightly different physical properties of all the isotopes of an element?

Q.

Explain why, the atomic masses of many elements are in fractions and not whole numbers.