Chemistry Questions & Answers - Free Online Practice

881.

0.499g 0f CuSO₄.xH₂O when heated to constant weight gave a residue of 0.346g. the value of x is? (Cu = 63.5, S = 32.0, O = 16, H = 1)

0.5

2.0

3.0

4.0

5.0

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Correct answer is D

No explanation has been provided for this answer.

882.

An organic compound contains 72% carbon, 12% hydrogen and 16% oxygen by mass. The empirical formula of the compound is

C₈H₂₂O₃

C₆H₁₀O₃

C₁₂H₁₂O

C₆H₁₂O

C₃H₆O

View answer & explanation

Correct answer is D

carbon = 72%, hydrogen = 12%, 16%

Dividing by the atomic weight we have for C = $\frac{5}{1}$ = 6

H = $\frac{12}{1}$ = 12

O = $\frac{16}{16}$ = 1

Divide by the smallest number, we have = $\frac{6}{1}$ = 6

H = $\frac{12}{1}$ = 12

O = $\frac{1}{1}$ = 1

The formula is C₆H₁₂O

883.

Which of the following conduct electricity?

sulfur

graphite

diamond

red phosphorus

yellow phosphorus

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Correct answer is B

No explanation has been provided for this answer.

884.

When 50cm³ of a saturated solution of sugar (molar mass 342.0g) at 40^oC was evaporated to dryness, 34.2g of dry solid was obtained. The solubility of sugar at 40^oC is

10.0 moles dm^-3

7.0 moles dm^-3

3.5 moles dm^-3

2.0 moles dm^-3

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Correct answer is D

No explanation has been provided for this answer.

885.

Which of the following groups of physical properties increases from left to right of the periodic table?

i. Ionization energy ii. Atomic radius iii. Electronegativity iv. Electron affinity

i and ii

i, ii and iii

iii and iv

i, iii and iv

View answer & explanation

Correct answer is D

Atomic radius is the distance from the atom's nucleus to the outer edge of the electron cloud. In general, atomic radius decreases across a period and increases down a group.