What is mass number? 

Important Questions on Structure of Atom

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 4

Which of the two has larger mass: electron or proton?

EASY

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 5

If Z = 3, what would be the valency of the element? Also name the element. 

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 6

Why did Rutherford select a gold foil in his $\mathrm{\alpha }$-particle scattering experiment? 

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 7

Atomic number of two elements are 20 and 18 respectively, but the mass number of both these elements is 40. What is the name given to such a pair of elements? Define these. 

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 8

Give two main differences between cathode rays and canal rays. 

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 9

What are $\mathrm{\alpha }$-particles? What are the charge and mass of $\mathrm{\alpha }$-particles? 

HARD

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 10

Explain:
(i) Nucleus of an atom carries positive charge.
(ii) Most of the space in an atom is empty.
(iii) The whole mass of an atom is present in the centre of the atom. 

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ of SCIENCE CHEMISTRY FOR Class IX>Chapter 4 - Structure of Atom>TEST YOURSELF>Q 11

Mercury ($+2$) ion contains $80$ protons, $78$ electrons and $120$ neutrons. Its mass number is _____.