Stoichiometric Calculations

Q.

What is the concentration of sugar$\left({\mathrm{C}}_{12}{\mathrm{H}}_{22}{\mathrm{O}}_{11}\right)$ in ${\text{mol L}}^{-1}$ if its $20\text{g}$ are dissolved in enough water to make up a final volume up to $2\text{L}$?

Q. The number of atoms in $1\text{mL}$ of ammonia gas at STP is:

1. $2.7\times {10}^{19}$
2. $1.08\times {10}^{20}$
3. $10.8\times {10}^{20}$
4. $5.4\times {10}^{19}$

Q. Find the total number of electrons present in $96\text{g}$ of $S{O}_4^{2-}$.

1. $5.781\times {10}^{25}$ electrons
   
2. $3.011\times {10}^{25}$ electrons
   
3. $50$ electrons
4. $98$ electrons

Q.

What is the molarity of pure water at $4°\mathrm{C}$?

Q. The amount of zinc required to produce $1.12\text{mL}$ of $H_2$ at STP on treatment with $dil.HCl$ will be: (Given: Molar mass of $Zn$= $65g/mol$)

1. $60\text{g}$
2. $0.65\text{g}$
3. $32.5\times {10}^{-4}\text{g}$
4. $6.5\text{g}$

Q. Haemoglobin contains $0.35\%Fe.$ Each haemoglobin unit contains four atoms of $Fe\left(56\text{g/mol}\right).$ The molar weight of haemoglobin (in kg) is:

Q. Assuming full decomposition, the volume of $C{O}_2$ released at STP on heating 9.85g of $BaC{O}_3$ (Atomic mass of Ba=137) will be

1. 0.84 L
2. 2.24 L
3. 4.06 L
4. 1.12 L

Q. The number of gram atoms in $3.2\text{g}$ of $Ca$ :

1. $3.2\text{g}$ atoms
2. $0.08\text{g}$ atoms
3. $0.8\text{g}$ atoms
4. $1.0\text{g}$ atoms

Q. Let a partially dried clay mineral contains $8\%$ water. The original sample contains $12\%$ water and $45\%$ silica and $43\%$ aluminium. The $\%$ of silica in the partially dried sample is nearly

1. $50\%$
2. $49\%$
3. $55\%$
4. $47\%$

Q.

Calculate the number of moles present in 32 g of Sulphur dioxide?

Q. How many grams of oxygen is required to completely react with $0.2\text{g}$ of hydrogen to yield water?

1. $1.8\text{g}$
2. $12\text{g}$
3. $16\text{g}$
4. $1.6\text{g}$

Q. Phosphine $\left(P{H}_3\right)$ decomposes to produce $P_4\left(g\right)\text{and}{H}_2\left(g\right)$. What would be the change in volume when $100\text{mL}$ of $P{H}_3\left(g\right)$ is completely decomposed?

1. $50mL$
2. $500mL$
3. $75mL$
4. $250mL$

Q. Calculate the mass of $C{O}_2$ produced by heating $20\text{g}$ of pure limestone $\left(CaC{O}_3\right)$.

1. 20 g
2. 10 g
3. 8.8 g
4. 5.5 g

Q. An element has the following natural abundances and isotopic masses: 90.92% abundance with $19.99\text{amu}$, 0.26% abundance with $20.99\text{amu}$ and 8.82% abundance with $21.99\text{amu}$. Calculate the average atomic mass of this element.

1. $80.52\text{amu}$
2. $25.45\text{amu}$
3. $20.16\text{amu}$
4. $15.89\text{amu}$

Q. How much carbon dioxide will be formed in the reaction when 25 grams of glucose and 40 grams of oxygen are made to react?
Reaction: $C_6{H}_{12}{O}_6+6O_2\to 6C{O}_2+6H_{2}O$

1. 24.2 g
2. 64.2 g
3. 48.6 g
4. 36.7 g

Q. In the reaction,
$4N{H}_3+5O_2\to 4NO+6H_{2}O$
when two moles of ammonia and three moles of oxygen are made to react completely, then:

1. 1 mole of $H_{2}O$ is produced
2. $N{H}_3$ will be in excess
3. 2 moles of NO is formed
4. Oxygen is completely consumed

Q.

A mixture of hydrogen and oxygen at one bar pressure contains 20% by weight of hydrogen. Find the partial pressure of hydrogen.

1. 0.2 bar

2. 0.4 bar

3. 0.6 bar

4. 0.8 bar

Q. If $N_A$ is the Avogadro’s number, then the number of valence electrons in $4.2\text{g}$ of nitride ions $\left(N^{3-}\right)$ is:

1. $4.2N_A$
2. $2.4N_A$
3. $1.6N_A$
4. $3.2N_A$

Q. 1 g of dry green algae absorbs $4.7\times {10}^{-3}$ mol of $C{O}_2$ per hour by photosynthesis. If the fixed carbon atom are stored as starch ($C_6{H}_{10}{O}_5{)}_n$, how long would it take for the algae to double their own weight assuming photosyntheseis takes place at constant rate?
Give the answer to nearest integer.

Q.

$22\mathrm{g}$ : $22\mathrm{g}$ of Carbon dioxide?

Q.

How many atoms are there in exactly $12\mathrm{g}$ of carbon?

Q. How many mol of potassium chlorate is to be heated to produce 5.6 litres of oxygen at $0{}^{\circ }\text{C}$ and 1 atm?

Q. Find the total number of electrons present in $1.6\text{g}$ of $C{H}_4$.

1. $6.023\times {10}^{23}$ electrons
2. $6.023\times {10}^{20}$ electrons
3. 10 electrons
4. 1 electron

Q. Percentage composition of hydrogen in benzene ($C_6{H}_6$) is .

1. $8\%$
2. $7.7\%$
3. $50\%$
4. $5\%$

Q. When sodium bicarbonate is heated, $1.806\times {10}^{24}$ molecules of water is obtained. Find the volume of $C{O}_2\left(g\right)$ obtained at STP.
$2NaHC{O}_3\stackrel{\Delta }{\to }N{a}_{2}C{O}_3+C{O}_2+H_{2}O$

1. $67.2\text{L}$
2. $55.0\text{L}$
3. $60.7\text{L}$
4. $70.5\text{L}$

Q. In a gravimetric determination of P, an aqueous solution of $Na{H}_{2}P{O}_4$ is treated with a mixture of ammonium and magnesium ions to precipitate magnesium ammonium phosphate $Mg\left(N{H}_4\right)P{O}_4.6H_{2}O$. This is heated and decomposed to magnesium pyrophosphate, $M{g}_2{P}_2{O}_7$ which is weighed. A solution of $Na{H}_{2}P{O}_4$ yielded 0.222 g of $M{g}_2{P}_2{O}_7$. What weight of $Na{H}_{2}P{O}_4$ is present originally?

(Atomic mass: $Na=23u,Mg=24u,P=31u,N=14u,O=16u,H=1u$)

1. $0.24$ g
2. $0.12$g
3. $0.18$ g
4. $0.36$ g

Q. What is the empirical formula of vanadium oxide, if $2.74g$ of the metal oxide contains $1.53g$ of metal?

1. $V_2{O}_3$
2. $VO$
3. $V_2{O}_5$
4. $V_2{O}_7$

Q. The empirical formula of a commercial ion exchange resin is $C_8{H}_{7}S{O}_{3}Na(M.M=206)$. The resin can be used to soften water according to the reaction:
$C{a}^{2+}+2C_8{H}_{7}S{O}_{3}Na\to Ca(C_8{H}_{7}S{O}_3{)}_2+2N{a}^{+}$
What would be the maximum uptake of $C{a}^{2+}$ by the resin expressed in $\text{mol/g}$ of resin?

1. $0.00243$
2. $0.0048$
3. $0.0243$
4. $0.243$

Q.

Paracetamol is a medicine used to treat pain and fever. Its molecular formula is${\mathrm{C}}_8{\mathrm{H}}_9{\mathrm{NO}}_2$ calculate the number of C, N, and O atoms in a 500 mg paracetamol tablet

Q. A ${5.0}^{}{\text{cm}}^3$ solution of $H_2{O}_2$ liberates $0.508\text{g}$ of iodine from acidified $KI$ solution. Calculate the strength of $H_2{O}_2$ solution in terms of volume strength at STP.