Neco Chemistry 2003 Past Questions and Answers

Question 26:

• 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 27:

• 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 28:

• 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 29:

• 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

Question 30:

• NECO 2003

The boiling point of water is higher than the boiling point of ethanol because ____________

A. The bonding in water is electrovalent (ionic) whereas the bonding in ethanol is convalent
B. The hydrogen bonding between water molecules is stronger than the hydrogen bonding between ethanol molecules
C. Water has a higher lattice energy than ethanol.
D. Water has hydrogen bonding between its molecules but ethanol has no hydrogen bonging between its molecules;
E. Water is a better solvent than ethanol.