English Medium इयत्ता ९ - CBSE Question Bank Solutions for Science

All the gases from cathode rays and anode rays when electricity is passed through them :What does the formation of cathode rays tell us about the atoms?

How does an electron differ from a neutron?

What is an atom ? How do atoms usually exist ?

The subatomic particle called electron was discovered by :

The ion of an element has 3 positive charges. The mass number of atom of this element is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

One nm is equal to :

The atom of an element X has 7 electrons in its M shell.
Is it a metal or a non-metal?

The atom of an element X has 7 electrons in its M shell.
What type of ion will be formed by an atom of element X? Write the symbol of the ion formed.
What could element X be?

An atom of element E contains 3 protons, 3 electrons and 4 neutrons :
(a) What is its atomic number?
(b) What is its mass number?
(c) Write the electronic configuration of the element E.
(d) State whether element E is a metal or non-metal. Why?
(e) What type of ion, cation or anion, will be formed by an atom of element E? Why
(f) Write the symbol of the ion formed by an atom of element E.
(g) What could element X be?

An atom of an element X may be written as `""_9^4"X"`
(a) What does the figure 9 indicate?
(b) What does the figure 4 indicate?
(c) What is the number of protons in atom X?
(d) What is the number of neutrons in atom X?
(e) What is the number of electrons in atom X?
(f) How many electrons are there in the outermost shell of an atom of element X?
(g) Write the symbol of ion formed by an atom of element X.

The electronic configuration of an element Z is 2, 8, 8.
(a) What is the atomic number of the element?
(b) State whether element Z is a metal or a non-metal.
(c) What type of ion (if any) will be formed by an atom of element Z? Why?
(d) What is special about the outermost electron shell of the atom of this element?
(e) Give the name and symbol of element Z.
(f) Name the group of elements to which Z belongs.

For the symbols H, D and T, write the subatomic particles (protons, neutrons and electrons) found in each one of them.

Which of the following statement is correct about the atom of an element ?

Find the mass of 2 moles of nitrogen atoms.

How many atoms are there in exactly 12 g of carbon-12 element ? (C = 12 u)

Calculate the number of moles in 12.044 × 1025 atoms of phosphorus.

Which has more atoms, 50 g of aluminium or 50 g of iron ? Illustrate your answer with the help of calculations.

(Atomic masses : Al = 27 u ; Fe = 25 u)

Which of the following has maximum number of atoms?

A change in the physical state can be brought about