(English Medium) ICSE Class 9 - CISCE Question Bank Solutions for Chemistry

The following element is given \[\ce{_20Z}\]. State the electronic configuration and state whether it is a metal, non-metal, or inert gas.

Explain the octet rule for the formation of –

Sodium chloride from a sodium atom and a chlorine atom.

Explain the octet rule for the formation of –

Nitrogen molecule from two nitrogen atoms.

Select the correct answer from the answer in the bracket to complete the sentence.

The maximum number of electrons in M-shell is _______.

Give a reason for the following:

The shells surrounding the nucleus of an atom are also called ‘energy levels’.

Give a reason for the following:

Helium is chemical extremely unreactive.

Fill in the blank with the correct word from the options given below:

Relative molecular mass of an element/compound is the number of times one ________ of the substance is heavier than −1/12that the mass of an atom of carbon [C₁₂].

Calculate the relative molecular mass of ZnCO₃.

Calculate the relative molecular mass of CaSO₄ [Zn = 65, S=32, O = 16, Ca = 40, C = 12]

Calculate the percentage of phosphorus in calcium hydrogen phosphate Ca(H₂PO₄)₂ .

Calculate the percentage of phosphorus in calcium phosphate Ca₃(PO₄)₂.

Calculate the percentage composition of each element in Potassium chlorate KCIO₃.

Urea is a very important nitrogenous fertilizer. Its formula is CON₂H₄. Calculate the percentage of carbon in urea. (C = 12, O = 16, N = 14 and H = 1)

The elements calcium, strontium and barium were put in one group or family on the basis of their similar properties.

What were those similar properties?

How does number of valence electrons vary on moving from left to right in the third period of a periodic table?

Sodium and aluminum have atomic numbers 11 and 13, respectively. They are separated by one element in the periodic table and have valencies 1 and 3 respectively. Chlorine and potassium are also separated by one element in the periodic table (their atomic numbers being 17 and 19, respectively) and yet both have valency 1. Explain.

Arrange the following:

Elements of group 1, in increasing order of reactivity

Arrange the following:

He, Na, Mg ( increasing order of melting point)

Arrange the following:

Chlorine, sodium, magnesium (increasing reducing character)

Calculate the percentage composition of calcium chloride.