Which of the following organic compounds can undergo both addition and substitution reactions?
Pentane
Benzene
Propane
Hexane
Correct answer is B
An example of benzene addition reaction is the formation of cyclohexane by a mix of benzene vapour and hydrogen passed over nickel catalyst; while chlorobenzene is formed by substitution reaction.
be very reactive and will attack ozone
be non-reactive and will not attack ozone
not change the level of ozone in the atmosphere
increase the level of ozone in the atmosphere
Correct answer is A
CFCs (Chlorofluorocarbons) have a lifetime in the atmosphere of about 20 to 100 years, and consequently one free chlorine atom from a CFC molecule can do a lot of damage, destroying ozone molecules for a long time
Which of the following separation techniques can be employed in obtaining solvent from its solution?
Evaporation
Distillation
Filtration
Precipitation
Correct answer is B
Distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation.
In the removal of water hardness, permutit is regenerated with a strong solution of
NaOH
Na\(_3\)SO\(_4\)
Na\(_3\)CO\(_3\)
NaCl
Correct answer is D
permutit water softener can be regenerated by washing the spent resin with brine( saturated sodium chloride solution). The solution ions replace the calcium or magnesium ions present in it.
\(CaR_{2(s)}\) + 2\(NaCl_{aq}\) → \(CaCl_{2(aq)}\) + 2\(NaR_{2(s)}\)
Which of the compounds is composed of Al, Si, O and H?
Epson salt
Limestone
Clay
Urea
Correct answer is C
Between the five main minerals found in clay, kaolinite is the most common. Kaolinite holds the chemical composition Al\(_{2}\) Si\(_{2}\)O\(_{5}\)(OH)\(_{4}\) and is an aluminum silicate material with a low “shrink-swell” capacity. It is a soft, white mineral but is often colored orange or red by iron oxide found in the soil.