General Science Class-7 (MCQs=1333)

An atom has atomic number 9 and mass number 19. How many neutrons are present in that atom?
a) 9        

b) 10                      
c) 19      
d) zero

Show answer Comments

---

Each shell can contain only a fixed number of electrons: the first shell can hold up to two electrons, the second shell can hold up to eight (2 + 6) electrons, the third shell can hold up to 18 (2 + 6 + 10) and so on. The general formula is that the nth shell can in principle hold up to 2(n²) electrons.

---

Electrons revolve around the nucleus in circular path called……..
a) orbit                                  

b) shell
c) energy level                     

d) all of these

Show answer Comments

---

The distribution of electrons in different shells is called……….
a) energy of electron          
b) electronic configuration
c) electronic revolution      

d) all of these

Show answer Comments

---

Which of the following formula is used for the distribution of electrons in different electronic shells?
a) 2n2    

b) 2n3                    

c) 2n4     

d) 3n2

Show answer Comments

---

The first shell of an atom is known as…shell.
a) K       

b) L                        

c) M       

d) N

Show answer Comments

---