Pure Chemistry MCQ Revision

X and Y, one is metal, one is non-metal.

since Y has more valence then X is metal and Y is non-metal and X has more electron shell since it has protons.

Possible salts

CaCl2 (aq)

CuCl2 (aq)

CaSO4 (s)

CuSO4 (aq)

Ca(NO3)2 (aq)

Cu(NO3)2 (aq)

Since the melting point and boiling point are low, it should be a simple molecular structure with weak intermolecular forces of attraction that can be overcome easily.

A represents the activation energy needed to break the bonds and B represent the energy given out as bonds are formed.

Thus D is the overall enthalpy change. Since it ask for the reverse reaction then it is C

CaCO3 + 2HCl --> CaCl2 + CO2 + H2O

for CO2:

24dm3 --> 1 mole

6 dm3 --> 0.25 mole

mole ratio of

CO2 : CaCO3

1 : 1

0.25 : 0.25

Molar Mass of CaCO3 = 100g

0.25 mole --> 25g

Therefore, % purity = (25/50) x 100% = 50 %

Heavy water has a higher molar mass as compared to normal water, and the boiling point will be slightly higher. Howeve,r most of the chemical properties will be similar.

The more C atoms in the molecule, the more soot (unburnt hydrocarbon) will be produced

Molar mass : Zn (65), V(51)

mole of  Zn = 32.5/65 =0.5 mole

mole of V = 10.2/51 = 0.2 mole

let charge of V be x.

0.5 (2+) = 0.2(x)

x = 5+

CaCO3 + 2HCl --> CaCl2 + CO2 + H2O

1 mole --> 24000 cm3

360 cm3 --> 0.015 mole

Ratio of CaCO3 : CO2

1:1

mole of CaCO3 = 0.015 mole

molar mass of CaCO3 = 100g

mass = 0.015 x 100 = 1.5g

% purity = 1.5/1.7 x 100% = 88.2%

1. neutralisation ( not redox)
2. redox
3. redox

There would be air in the test tube and tubing. Thus the main contaminant would be nitrogen gas.

by definition, isotopes are atoms with the same number of protons and diff number of neutrons

Aluminium oxide is amphoteric and neutralises the sodium hydroxide. Thus the pH decrease

The physical properties of members show a trend

• When aqueous sodium hydroxide is added in excess to sodium carbonate, no reaction takes place

• When dilute acid is added to sodium carbonate, carbon dioxide is evolved.

• Sodium carbonate is soluble in water and form a colourless solution.

• sodium carbonate is stable to heat.

The monomer must have one cooH and one NH2 function group

An alternative pathway with lower activation energy is only provided by a catalyst, not a higher temperature

When silver nitrate is added, PPT of silver chloride(white) and silver iodide(yellow) will be formed, respectively

The incorrect statement is that chloride ions are reduced at the anode, as they are oxidized.

The molecules with the greatest molar mass and longest chain are collected at the bottom. They have the highest boiling point and are hard to ignite

Heptane vapour will condense as it reaches the fractionating column; only hexane vapour will reach the condenser. As the thermometer will only measure the inlet of the condenser, the measured temperature will be constant at the boiling point of hexane until all the hexane has vaporized.

Experiment B has more starting reactant but lower concentration than A. Therefore, the curve will be less steep but finish higher.

Hydrolysis of polymers is a chemical process where water molecules break down polymer chains

acidic oxide neutralises base/alkali to form salt and water

CO is neutral.

Y would be noble gas and thus W is in group 16 with 6 valence electrons and need 2 more

Cl has 7 valence and need 1 more so the formula will be WCl2

AgNO3 + NaI --> NaNO3 + AgI

50.0 cm3 of 0.10 mol/dm3 silver nitrate, AgNO3 = 0.005 mole

150.0 cm3 of 0.05 mol/dm3 of sodium iodide, NaI, = 0.0075 mole

Reactant ions left = Na+ and I -

product ions = Na+ and NO3^-

The further the ink moved from the starting line, the more soluble it is in this solvent

Since its ion's charge is  2+, it is in group 2 and called Alkali Earth metal not alkali metal.

2,8,8,2 is calcium which is in period 4 as its atom have 4 electron shells.

Its oxide is basic.

As you move from left to right across a period, the number of protons in the nucleus increases, which leads to a stronger attraction for electrons. This increased attraction makes it more difficult for an atom to lose electrons,

Ammonium salt + Strong Alkali --> ammonia gas + water + salt

test for nitrate: add sodium hydroxide solution to the sample, followed by aluminum foil, and gently heat the mixture. If nitrate ions are present, they will be reduced to ammonia gas, which can be detected by its pungent smell or by its ability to turn damp red litmus paper blue. 

reactivity increases as it goes down the group.

2H2 + O2 --> 2H2O

for H2,

1 mole --> 2g

6 g of hydrogen =  3 mole

H2 : O2

2 :  1

3 mole : 1.5 mole

1.5 mole of O2 = 32 x 1.5 = 48g

Iron is above copper in the reactivity series. Iron will readily give away electrons to copper. Thus, iron will ionize easily to react with the oxygen in the air to rust.

% of N in (NH2)2CO = 46.65 %

% of N in (NH4)2SO4 = 21.2%

% of N in (NH4)3PO4 = 28.18%

% of N in NH4NO3 = 35%

The catalyst must remain unchanged at the end of the reaction.

Titration requires an acid (anion side) and a soluble base (cation side).

Only D fulfills the  soluble cation criteria

Lithium sulfate, potassium chloride, and sodium nitrate are all group 1 salts, where their cations will form soluble hydroxide.

Both compounds are giant ionic structures. But the magnesium ion charge is 2+ while the sodium ion is 1+. Thus, the electrostatic forces holding the ions together are stronger in magnesium chloride

Ca is cation and O is anion. They are opposite in charge and attract each other. Thus in the diagram, only black balls are bonded to white balls directly.

Sulfur is 2,8,6 so when it form an ion, it will be 2,8,8 which is the electron configuration of Argon