Year : 
2009
Title : 
Chemistry
Exam : 
NECO - BECE

Paper 1 | Objectives

21 - 30 of 47 Questions

# Question Ans
21.

C\(_6\)H\(_{12}\)O\(_6\)What is the molar mass of the compound above?[ H=1, C=12, O=16 }

A. 45

B. 61

C. 180

D. 123

E. 244

Detailed Solution

The compound above is identified as glucose
Carbon - 12 \(\times\) 6 atoms present
Hydrogen - 1 \(\times\) 12 atoms present
Oxygen - 16 \(\times\) 6 atoms present
= 72 + 12 + 96
= 180
22.

If the volume of a gas at 35°C is 60cm3, what would be its volume in cm3 at 273k?

A. 39.03

B. 46.81

C. 53.18

D. 67.69

E. 76.92

C
23.

Sulphur has an oxidation number of +4 in

A. H2S

B. H2S04

C. MgSO4

D. Na2SO3

E. S03

D
24.

Atomic size decreases

A. across a period from left to right

B. across a period from right to left

C. diagonally down the group

D. down a group

E. with decrease in atomic number

A
25.

A salt which loses its mass when exposed to air is

A. deliquescent

B. effervescent

C. Efflorescent

D. fluorescent

E. hygroscopic

C
26.

When air is passed through alkaline pyrogallol and then lime water, the gases left are

A. nitrogen and carbon (IV) oxide

B. nitrogen and noble gases

C. nitrogen and oxygen

D. nitrogen, carbon (VI) oxide and noble gases

E. the noble gases

B
27.

How many zones are present in a luminous Bunsen burner flame?

A. 2

B. 3

C. 4

D. 5

E. 6

C
28.

What mass of copper in gram would be deposited by a current of 1.00ampere passing for 965 seconds through copper(II) tertraoxosulphate (VI) solution? [Cu 63.5; If = 96500c]

A. 0.32

B. 0.64

C. 3.18

D. 6.35

E. 9.65

Detailed Solution

Recall that two faradays ( 2 X 96500 ) will be required to discharge 1 mole of a divalent ion like Cu.
2 X 96500 will deposit 63.5g of Cu
And 965C wiil deposit x-grams
CROSS MULTIPLY
(965 X 63.5) ÷ ( 2 X 96500)
= 0.3175
29.

Which of the following metals is NOT extracted by electrolysis?

A. Aluminium

B. Calcium

C. iron

D. Magnesium

E. Sodium

C
30.

The furring of kettles and boilers are caused by

A. calcium hydroxide

B. calcium hydrogen trioxocarbonate (IV)

C. calcium trioxocarbonate (IV)

D. calcium tetraoxocarbonate

E. magnesium tetraoxocarbonate (VI)

Detailed Solution

The furring of kettles or boilers - this is as a result of the decomposition of Ca(HCO3)2 into CaCO3, and this coats the inside of a kettle or boiler used in heating water containing dissolved Ca(HCO3)2.
21.

C\(_6\)H\(_{12}\)O\(_6\)What is the molar mass of the compound above?[ H=1, C=12, O=16 }

A. 45

B. 61

C. 180

D. 123

E. 244

Detailed Solution

The compound above is identified as glucose
Carbon - 12 \(\times\) 6 atoms present
Hydrogen - 1 \(\times\) 12 atoms present
Oxygen - 16 \(\times\) 6 atoms present
= 72 + 12 + 96
= 180
22.

If the volume of a gas at 35°C is 60cm3, what would be its volume in cm3 at 273k?

A. 39.03

B. 46.81

C. 53.18

D. 67.69

E. 76.92

C
23.

Sulphur has an oxidation number of +4 in

A. H2S

B. H2S04

C. MgSO4

D. Na2SO3

E. S03

D
24.

Atomic size decreases

A. across a period from left to right

B. across a period from right to left

C. diagonally down the group

D. down a group

E. with decrease in atomic number

A
25.

A salt which loses its mass when exposed to air is

A. deliquescent

B. effervescent

C. Efflorescent

D. fluorescent

E. hygroscopic

C
26.

When air is passed through alkaline pyrogallol and then lime water, the gases left are

A. nitrogen and carbon (IV) oxide

B. nitrogen and noble gases

C. nitrogen and oxygen

D. nitrogen, carbon (VI) oxide and noble gases

E. the noble gases

B
27.

How many zones are present in a luminous Bunsen burner flame?

A. 2

B. 3

C. 4

D. 5

E. 6

C
28.

What mass of copper in gram would be deposited by a current of 1.00ampere passing for 965 seconds through copper(II) tertraoxosulphate (VI) solution? [Cu 63.5; If = 96500c]

A. 0.32

B. 0.64

C. 3.18

D. 6.35

E. 9.65

Detailed Solution

Recall that two faradays ( 2 X 96500 ) will be required to discharge 1 mole of a divalent ion like Cu.
2 X 96500 will deposit 63.5g of Cu
And 965C wiil deposit x-grams
CROSS MULTIPLY
(965 X 63.5) ÷ ( 2 X 96500)
= 0.3175
29.

Which of the following metals is NOT extracted by electrolysis?

A. Aluminium

B. Calcium

C. iron

D. Magnesium

E. Sodium

C
30.

The furring of kettles and boilers are caused by

A. calcium hydroxide

B. calcium hydrogen trioxocarbonate (IV)

C. calcium trioxocarbonate (IV)

D. calcium tetraoxocarbonate

E. magnesium tetraoxocarbonate (VI)

Detailed Solution

The furring of kettles or boilers - this is as a result of the decomposition of Ca(HCO3)2 into CaCO3, and this coats the inside of a kettle or boiler used in heating water containing dissolved Ca(HCO3)2.