Chemistry Questions & Answers - Free Online Practice

2,746.

Which of the following bonds exist in crystalline ammonium chloride (NH₄Cl)?

Ionic and covalent

Ionic and co-ordinate

Ionic covalent and co-ordinate

Covalent , co-ordinate and metalllic

Ionic, covalent and metallic

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Correct answer is C

No explanation has been provided for this answer.

2,747.

The pressure on 100 cm³ of oxygen gas at 35°C is 750mm of Hg.What would be the volume of the gas if the pressure is increased to 1000mm of Hg without changing the temperature?

133.3 cm³

85 cm³

75 cm³

65 cm³

58.3 cm³

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Correct answer is C

P₁ = 750MHg V₁ = 100cm³ l₂ = 308k
P₂ = 100 mmHg V₂ = ?
But (P₁V₁)/(T₁) = ((P₂V₂)/(T₂) i.e (750 x 100)/(308) = (1000 x )/(V₂)/(308)
V₂ = (750 x 1000 x 308)/(308 x 1000) = 75 cm³

2,748.

0.07g of a hydride of carbon occupies 56.0cm³ at S.T.P. when vaporized and contains 14.29% by mass of hydrocarbon is(C = 12, H = 1)

CH₄

C₂H₂

C₂H₄

C₂H₆

C₃H₈

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Correct answer is C

% of H₂ = 14.29
% of C = 85.71
Divided by At wts
For H = (14.29)/(1) = 14.29
For C = (85.71)/(12) = 7.14
Dividing by smallest number we have the following:
For H (14.29)/(7.14) = 2
For C = (7.14)/(7.14) = 1
Emperical formula of the comp = CH₂
wt of hydride taht will occupy 22400 cm is 22400 x 0.7
56 = 28 = mole wt of hydride
X(CH₂) = 28
X(12 + 2) = 28 i.e 14x = 28x = 2
The formula of hydrocarbon is therefore C₂H₄