Atomic Number and Mass Number

Q.

The percentage of sulphur in an organic compound whose 0.32g produces 0.233g of $BaS{O}_4$ [atomic weight of Ba= 137, S=32] is

1. 1.0

2. 10.0

3. 23.5

4. 32.1

Q.

x gm of water is mixed with 69 gm of ethanol. The mole fraction of ethanol in the resulting solution is 0.6. What is the value of 'x' in gm.

1. 54

2. 36

3. 180

4. 18

Q.

The atomic weights of two elements A and B are 40 and 80 respectively. If x g of A contains y atoms, how many atoms are present in 2x g of B?

1. y/2

2. y/4

3. y

4. 2y

Q. 45. Mass of moving electron?

Q.

Show the formation of sodium ion.(atomic number of sodium($\mathrm{Na}$) is 11)

Q. 29. If there can be 3 values of spin quantum number then how many elements will be present in third period?

Q.

Q.

Which of the following has highest mass

1. 5 moles of nitrogen

2. 1 g atom of silver

3. 50 g of iron

4. atoms of carbon

Q. boron exist as two isotopes ^{10}B and ^{11}B if atomic mass of boron in periodic table is given to 10.81 what is the relative abundance of the heaver isotop?

Q. How many moles of Oxygen atoms are present in 88g of CO2? Options: a)2 b)4 c) 3 d)1

Q. The relative charges on an electron, a proton and a neutron respectively are:

1. $+1,+1,0$
2. $-1,+1,0$
3. $-1,0,+1$
4. $0,+1,-1$

Q. If the number of protons in $X^{2-}$ is 16, then the number of electrons in $X^{2+}$ will be:

1. 14
2. 16
3. 18
4. Cannot be determined

Q. Which of the following pair(s) is/are isodiaphers?

1. ${}_6^{14}Cand{}_{11}^{23}Na$
2. ${}_{12}^{24}Mgand{}_{11}^{23}Na$
3. ${}_2^{4}Heand{}_8^{15}O$
4. ${}_9^{19}Fand{}_6^{13}C$

Q. 65. B has two isotopes Boron 10 (19%) and Boron 11 (81%). The atomic mass of B is

Q. 97.To calculate number of neutron in chlorine atom , why mass number is taken as 35 rather than 35.5.?

Q. The atomic number and the mass number of an element M are 25 and 52 respectively.
The number of electrons, protons and neutrons in $M^{2+}$ ion respectively are:

1. 25, 25 and 27
2. 25, 27 and 25
3. 27, 25 and 27
4. 23, 25 and 27

Q.

According to the Bohr's model of a hydrogen atom, what would be the ratio of Bohr's radius of ${}_1$H${}^1$, ${}_1$H${}^2$ and ${}_1$H${}^3$ be?

1. 1:1:1

2. 2:3:4

3. 3:2:1

4. 1:4:9

Q. List out the differences between Isobars and Isotopes

Q.

If Z is the number of protons and A the number of nucleons, then the number of neutrons in an atom is given by

1. A + Z

2. A - Z

3. Z - A

4. None of the above

Q. the atomic number and atomic mass of iron or 26 and 56 respectively find the number of protons neutrons and electrons on its atom

Q. An element with mass number $81$ contains $31.7\%$ more neutrons as compared to protons. Assign the atomic symbol.

Q. Among the second period elements the actual ionization enthalpies are in the order $Li<B<Be<C<O<N<F<Ne$.

Q. Which of the following pair(s) of nucleides is/are isodiaphers?

1. ${}_6^{12}Cand{}_8^{16}O$
2. ${}_1^{1}Hand{}_1^{2}H$
3. ${}_1^{3}Heand{}_2^{4}He$
4. ${}_{25}^{55}Mnand{}_{24}^{52}Cr$

Q.

Three different atoms of hydrogen are represented as ${}_1{}^1\mathrm{H};{}_1{}^2\mathrm{H};{}_1{}^3\mathrm{H}$. Draw atomic structure of ${}_1{}^3\mathrm{H}$.

Q. The penultimate and outermost orbit of an element contains 10 and 2 electrons respectively. If the outermost orbit is the fourth orbit, then the atomic number of the element should be:

1. 12
2. 22
3. 32
4. 40

Q. How many moles of oxygen atoms is present in $80\%$ pure 20g of $C{O}_2$?

1. 0.73

2. 0.25

3. 1

4. 0.5

Q. "Thus we can conclude that electrons are basic constituents of all the atoms" explain the statemen

Q. Symbols ${}_{35}^{79}Br$ and ${}^{79}Br$ can be written, whereas symbols ${}_{79}^{35}Br$ and ${}^{35}Br$ are not acceptable. Answer briefly:

Q. An element is represented by ${}_Z{X}^A$, where Z is atomic number which is also equal to number of proton, A is mass number and X is symbol of the element.
Mass number (A) = Number of protons (Z) + Number of neutrons.
Isotopes: Atoms having same number of proton
Isobar: Elements having same mass number
Isotones: Elements having same number of neutron (A-Z)

An isotone of ${}_{40}^{90}Zr$ is _________.

1. ${}_{36}^{86}Kr$
2. ${}_{19}^{39}K$
3. ${}_{35}^{80}Br$
4. ${}_{50}^{119}Sn$

Q. If the electronic configuration of an element is $\left[Ar\right]$ $3d^{10}4s^{2}4p^3$, then elements belongs