Stoichiometry

Q.

Explain how to calculate the number of atoms of a certain element in a given mass of a compound.

Q.

What happens when Lead Nitrate reacts with Potassium Iodide?

Q. Show that in a first order reaction time required for completion of $99.9\%is10$ times of half-life $\left(t_{1/2}\right)$ of the reaction.

Q. The percentage composition of carbon by mole in methane is

1. 80%
2. 75%
3. 20%
4. 25%

Q.

Define the following:

(a) Unbalanced chemical equation

Q. Predict the products of the following reaction:

$A$: $C{H}_3-C{H}_2-C{H}_2-O-C{H}_3+HBr\to$

$B$:

$C$:

$D$: $(H_{3}C{)}_{3}C-O{C}_2{H}_5\stackrel{HI}{\to }$

Q.

Calculate the amount of ${\mathrm{CO}}_2$ that could be produced when
1) 1 mole of Carbon is burnt in the air
2) 1 mole of Carbon is burnt in 16 grams of ${\mathrm{O}}_2$
3) 2 moles of Carbon is burnt in 16 gram of ${\mathrm{O}}_2$

Q.

Why should curd and sour substances not be kept in brass or copper vessels?

Q. 50.0 kg of N2 (g) and 10.0 kg of H2(g) are mixed to produce NH3 (g).Calculate the NH3 (g) formed. Identify the limiting reagent in the production of NH3 in the situation

Q.

Which among the following statement(s) is (are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to (i) the formation of silver by decomposition of silver chloride (ii) sublimation of silver chloride (iii) decomposition of chlorine gas from silver chloride (iv) oxidation of silver chloride

1. (i) only

2. (i) and (iii)

3. (ii) and (iii)

4. (iv) only

Q.

Lead nitrate on heating gives

1. lead oxide

2. nitrogen dioxide

3. oxygen

4. all of these

Q. A bottle of sulphuric acid (d=1.787 g/ml) is labelled 86% by mass. What is the molarity of the solution? What volume of the acid is required to make 1L of 0.2M H2SO4?

Q. If $1\frac{1}{2}$ moles of oxygen combine with Al to form $A{l}_2{O}_3$, the weight of Al used in the reaction is: (atomic wt of Al = 27 u)

1. 27 g
2. 54 g
3. 40.5 g
4. 81 g

Q.

For a reaction, $\mathrm{A}+2\mathrm{B}⟶\mathrm{C}$, the amount of C formed by starting the reaction with 5 moles of A and 8 moles of B is:

1. 4 mol

2. 5 mol

3. 8 mol

4. 16 mol

Q.

Calaculate the molarity of 30 mL of 0.5M H2SO4 diluted to 500mL.

Q.

100ml of 1M NaOH is mixed with 50ml of1N KOH solution . What is Normality of mixture?

Q.

Write the chemical equation for the reaction between calcium and water.

Q. Why is Ka1=Ka2 for sulphuric acid in water

Q.

Write the chemical reaction for the Calcium carbide and water

Q. The combustion of one mole of benzene takes place at $298K$ and $1atm.$ After combustion, $C{O}_2\left(g\right)$ and $H_{2}O\left(l\right)$ are produced and $3267.0kJ$ of heat is liberated. Calculate the standard enthalpy of formation, ${△}_f{H}^{\ominus }$ of benzene. Standard enthalpies of formation of $C{O}_2\left(g\right)$ and $H_{2}O\left(l\right)$ are $–393.5kJmo{l}^{-1}$ and $–285.83kJmo{l}^{-1}$respectively.

Q.

How to balance the chemical equation.

Q.

Mole fraction of $\mathrm{A}$ in ${\mathrm{H}}_2\mathrm{O}$ is $0.2$ the molality of $\mathrm{A}$ in ${\mathrm{H}}_2\mathrm{O}$ is:

Q.

A metal forms two oxides, the higher oxide contains 80% metal, 0.72g of the lower oxide gave 0.8g of higher oxide on heating. Show that the data illustrates the law of multiple proportions?

Q.

Which of the following is 4-bromopent-2-ene?

1. 

2. 

3. 

4. 

Q.

On reacting ${\mathrm{NaHCO}}_3$ and Acetic acid, the gas evolved turns_____

Q.

Strong heating of ferrous sulphate leads to the formation of a brown solid and two gases. This reaction can be categorised as

1. displacement and redox.

2. decomposition and redox

3. displacement and endothermic

4. decomposition and exothermic

Q.

Show conversions:

Ethyne to Ethane

Q. Which of the following species is an electrophile?

1. $RN{H}_2$
2. $S{O}_3$
3. $\stackrel{-}{N}{O}_2$
4. $ROH$

Q. 250 ml of a sodium carbonate solution contains 2.65grams of Na2Co3. 10ml of this solution is added to x ml of water to obtain 0.001M Na2Co3 solution. What is the value of x in ml?

Q.

Which of the following compounds is most reactive towards nucleophilic addition reaction?

1. $\mathrm{PhCOPh}$

2. ${\mathrm{CH}}_3\mathrm{CHO}$

3. ${\mathrm{PhCOCPh}}_3$

4. ${\mathrm{CH}}_3{\mathrm{COCH}}_3$