Calculation of Mass Number for Isotopic Elements

Q. Question 10
If bromine atom is available in the form of, say, two isotopes ${}_{35}^{79}$Br (49.7%) and ${}_{35}^{81}$Br(50.3%), calculate the average atomic mass of bromine atom.

Q.

State the number of valence electrons in:

halogens

Q.

The relative atomic mass of a light element up to calcium is approximate…………..its atomic no.

Q.

State the number of valence electrons in:

alkali metals

Q.

A _____ atom is chosen as the reference atom to determine the relative atomic mass of other elements.

1. 
   Oxygen-16

2. 
   Carbon-12

3. 
   Hydrogen-1

4. 
   Carbon-13

Q.

The teacher took 2 beakers and said, "I am adding Cl-35 in the first beaker and adding Cl-37 in the second beaker. What do you think will be the valency of the two types of the chlorine atoms?"

1. Cl-35 has more valency than Cl-37

2. Cl-35 has less valency than Cl-37

3. equal

4. It cannot be determined.

Q.

what is mass number

Q. One atomic mass unit is equal to 1/12th of the mass ​of one atom of _______.​