Variation of Valency

Q.

What is the number of valence electrons in (i) Sodium ion (${\mathrm{Na}}^{+}$) (ii) Oxide ion (${\mathrm{O}}^{2¯}$)

Q. Write the electronic configuration for the following atoms:

1. Magnesium (Mg)
2. Neon (Ne)
3. Boron (B)
4. Fluorine (F)

Q.

The valency of nitrogen in $N_2$ molecule is:

1. 4

2. 1

3. 2

4. 3

Q.

Nitrogen is _____ in AlN. (monovalent/trivalent)

Q.

An element X is in the $1^{st}$ group of the modern periodic table. Its ion will be represented as:

1. $X^{+}$

2. $X^{-}$

3. $X^{2+}$

4. $X^{2-}$

Q. Define valency. What is the valency of the element with ​ atomic number 8? What is the compound formed by this element ​ with hydrogen?[3 Marks]​

Q.

An element X of group 15 exists as a diatomic molecule and combines with hydrogen at 773 K in presence of the catalyst to form a compound, ammonia which has a characteristic pungent smell.

Identify the element X. How many valence electrons does it have?

Q. Element X forms a chloride of formula $XC{l}_4$ which is solid with a low melting point. X would most likely belong to the same group in the periodic table as that of

1. Na
2. Mg
3. Al
4. Si

Q. An atom has an electronic configuration 2, 8, 5. To which of the following elements, mentioned below with their atomic numbers, it would be chemically similar?

1. F (9)
2. Na (11)
3. N (7)
4. Ar (18)

Q.

The valency of aluminium is :

1. 3

2. 1

3. 4

4. 2

Q. Lithium and sodium have the same number of ___.

1. valence electrons

2. electrons
3. shells
4. protons

Q. The number of electrons in the outermost shell of an atom helps us to calculate the _________________.

1. period number
2. group number
3. atomic number
4. atomic mass

Q. In an atom, electrons are arranged around the nucleus in various shells. What do ‘valence electrons’ refer to?

1. Electrons present in the first orbit.
2. Innermost electrons.
3. Total number of electrons.
4. Electrons present in outermost orbit.