Average and Relative Atomic Mass

Q.

What is relative atomic mass?

Q. What is the average atomic mass of Mg if the naturally occurring isotopes are ${}^{24}Mg$, ${}^{25}Mg$ and ${}^{26}Mg$. Their masses and abundances are as follows:

$\begin{array}{ccc}\text{Isotope}& \text{Atomic Mass}& \text{Isotopic abundance}\\ {}^{24}Mg& 23.98504& 78.70\%\\ {}^{25}Mg& 24.98584& 10.13\%\\ {}^{26}Mg& 25.98259& 11.17\%\end{array}$

1. 24.31
2. 25.68
3. 23.99
4. 24.98

Q.

what is the difference between atomic mass and mass number of an atom?

Q.

Oxygen exists in three isotopic forms with mass numbers 16, 17, and 18. The percentage abundances of these isotopes are $81\%$, $9\%$, and $10\%$, respectively. Calculate the average atomic mass of the element.

1. 16.9

2. 17.2

3. 16.29

4. 16.5

Q. An element A exist in two isotopic forms A15 and A16.if the average atomic mass of A was found to be 15.24.then find the % relative aboundance of A15 will be

Q.

The mass number of an atom whose unipositive ion has $10$ electrons and $12$ neutrons is

1. $22$

2. $23$

3. $21$

4. $20$

Q. The average atomic mass represents the average of all the naturally occurring isotopes of the element.

1. True
2. False

Q. Calculate the relative molecular mass of carbon dioxide.

Q.

The atomic mass of an element is $197$and its atomic number is $79$. Find the number of protons, neutrons, and electrons.

Q.

Define RAM based on hydrogen as well as carbon-12 scale.

Q.

Write the formulae for Sodium chloride and calculate the molecular mass for Sodium chloride.

Q.

If an elements atomic number is 23 and its mass number is 47, what will be the number of neutrons present in one atom of the element?

Q. What is the relative atomic mass of cadmium?

1. 112.411 amu
2. 20.00 amu
3. 21.00 amu
4. 20.43 amu

Q. The average mass of the atom as compared to ${\frac{1}{12}}^{th}$ the mass of one carbon-12 atom is known as :

1. relative molecular mass
2. relative atomic mass
3. molecular mass
4. atomic mass

Q.

An atom contains $22$ neutrons in its nucleus and $18$ electrons around it.

1. It contains _____ protons in its nucleus.
2. Its atomic number is _____ .
3. Its mass number is _____ .

Q.

If the mass number of an element is 31 and it contains 15 electrons, then what is the number of neutrons in it? What is its atomic number?

Q.

A compound of relative molecular mass 34 and empirical formula $\mathrm{HO}$ has the molecular formula __________

Q.

A certain sample of element Z contains 60% of ${}_{}{}^{69}Z$ and 40% of ${}_{}{}^{71}Z$. What is the relative atomic mass of element Z in the sample ?

1. $69.2$

2. $69.8$

3. $70.0$

4. $70.2$

Q. What is the relative molecular mass of sodium sulphate? (The relative atomic masses of $Na,S$ and $O$ are $23u,32u$ and $16u$ respectively)

1. 140
2. 142
3. 146
4. 148

Q.

The atom of an element has 20 protons, 20 electrons, and 20 neutrons:

What is the mass number of the element?

Q. The table given below is showing information about the isotopes of chlorine. Calculate the average atomic mass of chlorine using the given data.​ [2 marks]
\begin{tabular}{|c|c|c|} \hline Isotope & Atomic Mass & \% Abundance \\ \hline Chlorine \( -35 \) & \( 34.96 u \) & 75 \\ \hline Chlorine \( -37 \) & \( 36.96 u \) & 25 \\ \hline \end{tabular}

Q. What is the atomic mass of sodium?

1. $20g/mol$
2. $11g/mol$
3. $23g/mol$
4. $22g/mol$

Q.

What do you understand by 1amu?

Q.

What is the mass of $4g$ atom of$Ag$?

Q. Let us take the example of Bismuth. It's atomic number is 83 . Then how do we identify whether its atomic sixe increases or decreases?

Q. The relative atomic mass of hydrogen atom is:

1. $1$
2. $1.08$
3. $1.008$
4. $1.0008$

Q. A certain sample of element Z contains 60% of ${}^{69}Z$ and 40% ${}^{71}Z$ . What is the relative atomic mass of element Z in this sample?

1. 69.8
2. 70
3. 69.2
4. 70.2

Q. $1u=$ ?

1. The mass of one atom of the carbon-12 isotope
2. $1/12$th the mass of one atom of the carbon-12 isotope
3. $1/12$th the mass of one atom of the carbon-16 isotope
4. The mass of one atom of the carbon-16 isotope

Q.

Define gram molecular mass.

Q. Calculate the no. of atoms in: