Isotopes and Isobars

Q.

Why is the atomic mass of chlorine taken as $35.5\mathrm{u}$ and not a whole number like $36\mathrm{u}$ or $35\mathrm{u}$? Explain.

Q.

The atomic number of the element unnilennium is

1. $109$

2. $102$

3. $119$

4. $108$

Q.

The element boron occurs in nature as two isotopes having atomic masses 10u and 11u. What are the percentage abundances of these isotopes in a sample of boron having average atomic mass of 10.8u.

Q. How many number of neutrons are there in tritium?

1. Two
2. Three
3. Four
4. One

Q.

Isotopes have same ______but different______.

Q. Isotopes of an element have the same atomic number but a different ________.

1. valency
2. mass number
3. number of protons
4. number of electrons

Q.

Why are the physical properties of all the iso­topes of an element different?

Q.

Protium, Deuterium and Tritium are isotopes of:

1. Rhodium

2. Sodium

3. Hydrogen

4. Helium

Q.

If the relative atomic mass of boron is $10.8$, then calculate the percentage of its isotopes ${}_5{}^{10}\mathrm{B}$ and ${}_5{}^{11}\mathrm{B}$ occurring in nature.

Q.

What is the fifth symbol on the periodic table?

Q.

${}_1{}^{}\mathrm{H}$¹ is isotopes of hydrogen. Draw their structures showing clearly the number of protons; neutrons and electrons. Also, state their common names.

Q.

What is the value of 1 atomic mass unit in terms of grams?

1. $1.66\times {10}^{-24}g$

2. $12.66\times {10}^{-24}g$

3. $0.66\times {10}^{-24}g$

4. $0.166\times {10}^{-23}g$

Q. The ratio of the mass of ${}^{12}C$ atom to that of an atom of element= X (whose atomicity is four) is 1:9. The molecular mass element X is:

1. $480gmo{l}^{-1}$
2. $432gmo{l}^{-1}$
3. $36gmo{l}^{-1}$
4. $84gmo{l}^{-1}$

Q.

What are humans made of?

Q.

What is the reason for fractional atomic mass of some elements?

Q.

Gold : noble metal :: Helium : ________

1. Gas

2. Noble Gas

3. Non-Metal

4. Metal

Q. Atomic mass of boron is 10.81. It has two isotopes with 80% and 20% abundance respectively. The atomic mass of the isotope having 80% abundance is 11.01. The atomic mass of the other isotope is:

1. 10.81
2. 11.01
3. 10.01
4. 21.82

Q. Three isotopes of an element have mass numbers, $M$, $(M+1)$ and $(M+2)$. If the mean mass number is $(M+0.5)$ then which of the following ratios may be accepted for $M$, $(M+1)$, $(M+2)$ in that order?

1. $1:1:1$
2. $4:1:1$
3. $3:2:1$
4. $2:1:1$

Q. Isotopes of an element have
(a) the same physical properties (b) different chemical properties
(c) different number of neutrons (d) different atomic numbers.

Q. An element has two isotopes with atomic masses $(A-1)$ and $(A+3)$ respectively. The average atomic mass is $A$. Calculate the mole percentage of the heavier isotope.

1. $35$%
2. $25$%
3. $45.35$%
4. None of these

Q.

___ are atoms of the same element, which have the same number of protons but different mass numbers.

Q. The average atomic mass of a mixture containing 79 mole percent of ${}^{24}Mg$ and remaining 21 mole percent of ${}^{25}Mg$ and ${}^{26}Mg,$ is 24.31. Find the mole percent of ${}^{26}Mg$:

1. 5
2. 20
3. 10
4. 15

Q.

${}_{20}{}^{40}\mathrm{Ca}$ and ${}_{18}{}^{40}\mathrm{Ar}$ are called isotopes.

1. True
2. False

Q.

Where can we find deuterium?

Q. In radioactive isotope of hydrogen, 2 neutrons are present.

1. True
2. False

Q. Match the given pair of elements with the corresponding relation between them.

1. Isobars
2. Isotones
3. Isotopes

Q. A) What are isotopes? Give two examples of isotopes of elements.

[2 Marks]

B) Give any three applications of isotopes.

[3 Marks]
[APSCERT]

Q. The number of neutrons present in the radioactive isotope of hydrogen is :

1. 0
2. 1
3. 2
4. 3

Q.

What are isotopes? Write three isotopes of hydrogen.

Q.

Why is it that elements have fractional atomic mass?