AS & A Level Chemistry 2.3 Formulae : Exam Style Questions Paper 1

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Question:

Substance Q is a hydrocarbon. When 1.00 g of Q is completely burned, 3.22 g of carbon dioxide is produced. What could be the identity of Q?

A cyclohexene

B cyclopentane

C ethene

D pentane?

▶️Answer/Explanation

Ans:A

Question:

X and Y are oxides of different Period 3 elements. If one mole of X is added to water, the solution formed is neutralised by exactly one mole of Y. What could be the identities of X and Y?

▶️Answer/Explanation

Ans:D

Question

For which hydrocarbon are the molecular and empirical formulae the same?

A butane

B ethane

C pent-1-ene

D propane

▶️Answer/Explanation

ANS:D

Question

Compounds $\mathrm{J}$ and $\mathrm{K}$ each contain $40 \%$ carbon by mass.
What could $\mathrm{J}$ and $\mathrm{K}$ be?

▶️Answer/Explanation

Ans:B

Question

Compound X contains the elements C, H and O only. 2.00 g of X produces 4.00 g of carbon dioxide and 1.63 g of water when completely combusted.
What is the empirical formula of X?
A $CHO_2$ B $C_2H_2O$ C $C_2H_4O$ D $CH_2O_2$

Answer/Explanation

Ans: C

Question

A student reacts 1 mol of copper with concentrated nitric acid to produce 1 mol of copper(II) nitrate, 2 mol of water and substance X. No other product is formed. Substance X does not contain copper or hydrogen.
What could be substance X?
A $N_2$ B $N_2O$ C NO D $NO_2$

Answer/Explanation

Ans: D

Question

2.0 g of ammonium nitrate, NH₄NO₃, decomposes to give 0.90 g of water and a single gas.

What is the identity of the gas?

A NO B NO₂ C N₂O D N₂

Answer/Explanation

Answer C

Question

Four elements, W, X, Y and Z, have electronic configurations as shown.

Which formulae represent compounds that have boiling points below room temperature?
1 WX₂
2 YX
3 Z₂X

Answer/Explanation

Answer D

Question

Sodium reacts with 1 mol of compound Y to produce 1 mol of H₂(g).

Which compound could Y be?

A CH₃CH₂CH₂CH₂OH
B (CH₃)₃COH
C CH₃CH₂CH₂CO₂H
D CH₃CH(OH)CO₂H

Answer/Explanation

Answer D

Question

An organic molecule W contains 3 carbon atoms. It requires 4.5 molecules of oxygen for complete combustion.

What could W be?

A propane
B propanoic acid
C propanone
D propan-1-ol

Answer/Explanation

Answer D

Question

The M_r of compound X is 72. The composition by mass of X is 66.7% carbon, 11.1% hydrogen and 22.2% oxygen. X gives an orange precipitate with 2,4-dinitrophenylhydrazine reagent. X does not react with Fehling’s reagent.

What can be deduced from this information?

1 X is a carbonyl compound.

2 X is a ketone.

3 X is butanone.

Answer/Explanation

Answer A

Question

Compound Q contains 40% carbon by mass.
What could Q be?
1 glucose, C₆H₁₂O₆
2 starch, (C₆H₁₀O₅)n
3 sucrose, C₁₂H₂₂O₁₁

The responses A to D should be selected on the basis of

Answer/Explanation

Answer:

Question

71.0 g of chlorine, $Cl_2$, react with an excess of sodium hydroxide solution at a particular
temperature. The reaction produces exactly 35.5 g of product X.
What is product X?
A $H_2O$ B NaCl C NaClO D $NaClO_3$

Answer/Explanation

Ans: D

Question

The elements Cl , Mg, Si and S are all in Period 3.
What is the correct sequence of the melting points of these elements, from lowest to highest?

Answer/Explanation

Ans: A

Question

The complete combustion of 2 moles of a straight chain alkane produces 400 $dm^3$ of carbon dioxide measured at 301K and 1 × $10^5$Pa. Carbon dioxide can be assumed to behave as an ideal gas under these conditions.

What is the formula of the straight chain alkane?

A $C_8H_{18}$ B $C_{16}H_{34}$ C $C_{20}H_{42}$ D $C_{40}H_{82}$

Answer/Explanation

Ans: A

Question

Which formula represents the empirical formula of a compound?
A $C_2H_4O$ B $C_2H_4O_2$ C $C_6H_{12}$ D $H_2O_2$

Answer/Explanation

Ans: A

Question

1.15 g of a metallic element needs 300 cm³of oxygen for complete reaction, at 298K and 1 atm pressure, to form an oxide which contains O^2– ions.

What could be the identity of this metallic element?

A calcium
B magnesium
C potassium
D sodium

Answer/Explanation

Answer: D

Question

The reaction between acidified dichromate(VI) ions, Cr₂O₇^2–, and aqueous Fe²⁺ ions results in the dichromate(VI) ions being reduced to Cr³⁺ ions.

What is the correct equation for this reaction?

A $Cr_{2}O_{7}^{2-} + Fe^{2+} + 14H^{+} \rightarrow 2Cr^{3+} + Fe^{3+} + 7H_{2}O$

B $Cr_{2}O_{7}^{2-} + 2Fe^{2+} + 14H^{+} \rightarrow 2Cr^{3+} + 2Fe^{3+} + 7H_{2}O$

C $Cr_{2}O_{7}^{2-} + 3Fe^{2+} + 14H^{+} \rightarrow 2Cr^{3+} + 3Fe^{3+} + 7H_{2}O$

D $Cr_{2}O_{7}^{2-} + 6Fe^{2+} + 14H^{+} \rightarrow 2Cr^{3+} + 6Fe^{3+} + 7H_{2}O$

Answer/Explanation

Answer: D

Question

The hydrocarbon C17H36 can be cracked. Which compound is the least likely to be produced in this reaction?
A $C_{3}H_{8}$

B $C_{4}H_{8} $

C $C_{8}H_{16} $

D $C_{16}H_{34}$

Answer/Explanation

Ans:D

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