It is not possible to measure the atomic radius precisely since the electron cloud surrounding the atom does not have a sharp boundary. One practical approach to estimate the size of an atom of a non-metallic element is to measure the distance between two atoms when they are bound together by a single bond in a covalent molecule and then dividing by two. For metals, we define the term "metallic radius" which is taken as half the internuclear distance separating the metal cores in the metallic crystal. The van der Waal's radius represents the overall size of the atoms which includes its valence shell in a non bonded situation. It is the half of the distance between two similar atoms in separate molecules in a solid. The atomic radius decreases across a period and increases down the group. Generally, same trends are observed in case of ionic radius. The ionic radius of the species having the same number of electrons depends on the number of protons in their nuclei.

Which of the following statements is correct?

Metallic radius refer to metals only and is greater than covalent radius.
Metallic radius refer to metals only and is smaller than covalent radius.
Generally covalent radius refer to non-metals as well as metals in bonded state (Covalent bond).
Atomic radii of noble gases are expressed as van der Waal's radii which are smaller than metallic radii.

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Q. Reaction between X and Y forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z?

High melting point
Low melting point
Occurs as solid
Conducts electricity in molten state

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Q. Mention the type of bonding we can observe from the following Lewis dot structure.

(1)

(2)

(3)

1) Single bond

2) Double bond

3) Triple bond
1) Single bond

2) Triple bond

3) Double bond

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Q. The one which is composed of all the three kinds of bond
(ionic, covalent and coordinate bond )

Carbon tetrachioride
Ammonia
Sodium chloride
Ammonium chloride

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Q. Element 'M' forms a chloride with the formula

M C l_{2}

which is solid with high melting point. What type of bond is in

M C l_{2}

? Write the formula of the compound when M combine with sulphur, oxygen and nitrogen.

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Q. the carbon triple bond distance is less than C=C and C-C bond distances

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Which of the following statements regarding the periodic trends of chemical reactivity of the alkali metals and the halogens is correct?

The reactivity decreases in the alkali metals but increases in the halogens with increase in atomic number
In alkali metals the reactivity increases but in the halogens it decreases with increase in atomic number down the group.
Chemical reactivity increases with increase in atomic number down the group in both the alkali metals and halogens.
In both the alkali metals and the halogens, the chemical reactivity decreases with increase in atomic number down the group.

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An atom X has three electrons more than a noble gas configuration. What type of ion will it form?

Write the formula of its a) Sulphate b) Nitrate

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Q. Write the chemical formula and formula unit masses of:
(i) magnesium carbonate
(ii) aluminium oxide
[5 Marks]

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Choose the incorrect option based on the data provided in the table below.

Element/ Compound	Atomicity	Molecular Formula	Empirical Formula
A	3	$C O_{2}$	-
B	-	$C_{6} H_{12} O_{6}$	-
C	2	-	O

Molecular formula of C is $O_{2} .$
Empirical formula of A is $C O_{2}$ .
Empirical formula of B is ${CH}_{2} O$ .
Atomicity of B is 6

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