What are the possible oxidation numbers of an element if its atomic number is 17?

• A. -1 and 7
• B. -1 and 6
• C. -3 and 5
• D. -2 and 6

The molarity of 5% by weight of aqueous solution of tetraoxosulphate(VI) acid [molecular weight = 98] is

• A) 0.537 moldm^?3
• B) 0.208 moldm^?3
• C) 0.551 moldm^?3
• D) 0.333 moldm^?3

Considered the reaction: H⁺(aq) + OH^- (aq) → H₂O (l). The energy change taking place in the reaction above is enthalpy of

• A. formation
• B. hydration
• C. neutralization
• D. solution

Which is the temperature of a given mass of a gas initially at 0°C and 9 atm, if the pressure is reduced to 3 atm at constant volume?

• A. 91K
• B. 182K
• C. 273K
• D. 819K

One advantages of detergents over soap is that detergents?

• A. are easier to maufacture
• B. foam more than soap
• C. form soluble salts with hard water
• D. are able to deter germs more than soap

The most common ores of iron include

• A. haematite, malachite and limonite
• B. chalcolite, calamine and bornite
• C. magnetite, haematite and bornite
• D. magnetite, chalcolite and bornite

Choose the correct answer in the option above. Which of the following is a primary amine?

• A) A
• B) B
• C) C
• D) D

50cm\(^3\) of a saturated solution of KNO\(_3\) at 40\(^{\circ}\)C contained 5.05g of the salt. What is the solubility of KNO\(_3\) at 40\(^{\circ}\)C [K = 39, N = 14, O = 16]

• A)
  1.0moldm\(^{-3}\)
• B)
  1.5moldm\(^{-3}\)
• C)
  2.0moldm\(^{-3}\)
• D)
  5.0moldm\(^{-3}\)

Carbon exist naturally in the combined state as

• A. graphite
• B. coal
• C. diamond
• D. wood

Cathode rays causes an object placed behind a perforated anode to cast a shadow on the screen. This observation shows that the rays

• A) are positively charged
• B) are negatively charged
• C) have mass
• D) travel in straight lines