Neco Chemistry Past Questions and Answers

Question 66:

• NECO 2003

What is the number of moles of NaHCO₃in 250cm³ of its solution if the solution contains 8.4 g of NaHCO₃ in 1 dm³ of the solution. [Na = 23, 0 = 16, C = 12, H = 1)

A. 1
B. 0.25
C. 0.05
D. 0.025
E. 0.01

Question 67:

• NECO 2003

Which statement is NOT true about the composition of starch?

A. It contains only the atoms of carbon, hydrogen oxygen
B. It is a polysaccharide
C. Its empirical formula is C₂H₂0.
D. It is made from the monomerC₆H₁₂O₆.
E. The hydrogen and oxygen atoms are in the ratio 2:1.

Question 68:

• NECO 2003

Chlorine is used in water purification because it ____________

A. Bleaches impurities in the water
B. Decolorizes water
C. Destroys bacteria
D. Is extremely soluble in water
E. Is pleasant tasting

Question 69:

• NECO 2003

The number of hydrogen ions in 1.0dm6.00x10³ of a 0.25 mole dm6.00x10^-3 tetraoxosulphate(Vl) acid solution is
[Avogadro constant = 6.0 x 1 0]

A. 1.45x10²³
B. 1.50 x l0²³
C. 3.00x10²³
D. 3.15x10²³
E. 6.00x10²³

Question 70:

• NECO 2003

B is an isotope of the element \(^{238} _{92}Ur\). The isotope B has ____________

A. 46 protons and 119 neutrons
B. 92 protons and 92 neutrons
C. 92 protons and 146 neutrons
D. 92 protons and 238 neutrons