Question

5 questions h plz ans all
Q1. what is meant by atomicity? explain with two examples?
Q2. what is atmosphere fixation of nitrogen?
Q3. define velocity with its S.I unit?
Q4. state the law of conservation of mass . give one example to illustrate this law?
Q5. how many moles are 5 grams of calcium? (atomic mass of calcium=40u)​

Answer 1

Q1.What is  meant by atomicity ?explain with two example?

A1.The number of element present in a compound of that particular element is called atomicity.

Example:--

• Chlorine $(Cl_2)$

In chlorine , two atoms of chlorine reacts and shares there electrons to form a compound chlorine .So, we can say that number of atoms in chlorine is 2.

• Hydrogen in Hydrogen chloride (HCl)

$H_2 + Cl_2 \longrightarrow 2HCl$

Here one volume of hydrogen reacts with one volume of chlorine to form two volumes of hydrogen chloride.

Each volume of hydrogen contains two atoms , so atomicity of hydrogen is 2.

Q2.What is  atmosphere fixation of nitrogen?

A2. Coversion of nitrogen present in atomsphere into its nitrogenous compound due to lighting discharge is called atomspheric fixation of nitrogen.

Q3.Define velocity with its  S.I unit ?

A3. Velocity is defined as the distance covered by an body in per unit time within a particular direction.

$VELOCITY =\dfrac{Displacement}{Time}$

S.I unit of displacement = metres  (m)

S.I unit of time = second(s)

So ,

S.I unit of velocity =$\dfrac{m}{s}$

S.I unit of velocity =$ms^{-1}$

Q4 What is law of conservation of mass.Give one example to illustriate this law?

A4.Law of conservation of mass states that matter can neither be created nor can can be destroyed by chemical or physical processes but can be changed from one form to another.

Example:-

When a piece of ice melts it just changes its state to water of same mass and when this water is heated it will give vapours of same mass.

Q5.How many moles are 5 grams of calcium have?(atomic mass of calcium = 40 u)

A.5 We know,

1 mole = 1 gram per molecule

40 g of calcium have  = 1 mole

5 g of calcium will have =$\dfrac{5 \times 1}{40}$

5 g of calcium will have= 0.125 moles.