\(1.2 \times 10^{22}\)
\(1.2 \times 10^{23}\)
\(2.4 \times 10^{22}\)
\(2.4 \times 10^{23}\)
Correct answer is A
\(1mole = 6.02 \times 10^{23} ions\)
\(0.02moldm^{-3} = 0.02 \times 6.02 \times 10^{23}\)
=\(0.1204 \times 10^{23} = 1.204 \times 10^{22}\)
\(\approxeq 1.2 \times 10^{22}\)
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\(NaR_{2(s)}\)