Variable Valency Representing

Q.

Prepare a chart of any 20 compounds and write the molecular formula

Q. The atomic number of sodium is 11. How many valence electrons does it have?

1. 3
2. 9
3. 2
4. 1

Q.

Two or more atoms joined together chemically in a fixed proportion by mass are called molecules.

1. law of constant proportion

2. law of conservation of mass

Q. What will be the valency of calcium with respect to chlorine?

1. 1
2. 3
3. 2
4. 0

Q.

What is variable valency ? Give two examples of elements showing variable valency.

Q.

Why neon, helium and argon have zero valences?

Q.

Symbol of caustic soda and caustic potash and potassium

Q.

Write the chemical formula of Nitric acid.

Q.

Calcium nitrate is the chemical name for marble chips.

1. True
2. False

Q. What is the correct chemical formula for sodium oxide?

1. $N{a}_2{O}_3$
2. $N{a}_{2}O$
3. $Na{O}_2$
4. $NaO$

Q.

Write down the name of the ${\mathrm{Na}}_2{\mathrm{SO}}_4$

Q.

Which of the following is a chemical formula of zinc oxide?

1. ZnO

2. Zn₂O

3. ZO

4. Z₂O

Q.

Why is primary valency is Non-Directional?

Q. Find the valency of calcium with respect to oxygen.

1. 1
2. 2
3. 7
4. 6

Q.

Sugar is a compound which contains carbon, hydrogen, nitrogen and oxygen atoms.

1. True

2. False

Q.

Give the chemical formula for the compound and compute the ratio by mass of combining elements in magnesium sulfide.

Q.

Correct formula of ferric sulphate is

1. ${\mathrm{FeSO}}_4$

2. $\mathrm{Fe}{\left({\mathrm{SO}}_4\right)}_2$

3. ${\mathrm{Fe}}_3{\left({\mathrm{SO}}_4\right)}_2$

4. ${\mathrm{Fe}}_2{\left({\mathrm{SO}}_4\right)}_3$

Q.

Write the chemical formula of Hydrochloric acid.

Q. What is a chemical formula ? What is the rule for writing a formula correctly ?

Q. What is the valency of zinc in the compound ZnS?

1. 4
2. 3
3. 2
4. 1

Q.

Give one word for following statement.

Combining capacity of an element.

Q.

Define formula of a compound.

Q. What is the valency of potassium (atomic number = 19)?

1. Nine
2. Seven
3. Two
4. One

Q.

What is the empirical formula for magnesium hydroxide (milk of magnesia)?

Q.

An astronaut gets thirsty on the moon. So, he uses a special equipment to make water by combining hydrogen and oxygen. What can you say about this water made on the moon?

1. It will be different.

2. On moon the water will have lighter mass than on earth.

3. It will be the same.

4. On moon the water will have heavier mass than on earth

Q.

How are the elements having variable valency named? Give Two examples.

Q.

Write the formulae of the following chemical compounds:
Ammonia

Q. $11,17,10$ are the atomic number of elements $X,Y,$ and $Z.$
Write the molecular formulae of the compound formed when any two of the above element are combined.

Q.

Write the rules of writing a chemical formula.

Q.

What do you understand by the term variable valency?