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WAEC SSCE - Chemistry - 2018 (Objective)

Question 1 Report

In which of the following compounds does hydrogen form ionic compounds?

CH\(_{4}\)

HCl

NH\(_{3}\)

NaH

Answer Details

Out of the given compounds, only NaH (sodium hydride) contains ionic bonds involving hydrogen. In NaH, hydrogen has a negative charge (H\(^-\)) and sodium has a positive charge (Na\(^+\)). This results in the formation of an ionic compound. In the other compounds, hydrogen forms covalent bonds. In CH\(_4\) (methane), hydrogen shares electrons with carbon to form four covalent bonds. In HCl (hydrogen chloride), hydrogen shares electrons with chlorine to form a single covalent bond. In NH\(_3\) (ammonia), hydrogen shares electrons with nitrogen to form three covalent bonds. Therefore, only NaH contains ionic bonds involving hydrogen, while the others have covalent bonds.

Read lesson note on Chemical Combination (JAMB)

Chemical Combination

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Question 11 Report

What is the mass of solute in 500\(cm^{3}\) of 0.005\(moldm^{-3}\) \(H_{2}SO_{4}\)? ( H = 1, S = 32.0, O=16.0)

0.490g

0.049g

0.245g

0.0245g

Answer Details

n = cv where n = no of mole, c = molar concentration(mol/dm3) and v = volume( dm3)

volume = 500

$c m^{3}$ $c m^{3}$ $c m^{3}$
$c m^{3}$ $c m^{3}$ $c m^{3}$ $c m^{3}$ $c m^{3}$ = 0.5dm3, c = 0.005 $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$
$m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$
$\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ = 0.0025 = $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$
$\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ (where 98g/mol is the molar mass of H2SO4)

$c m^{3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$ $m o l d m^{- 3}$

number of mole(n) = c x v = 0.5 X 0.005 = 0.0025mol.

but n = $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{m o l a r m a s s}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$ $\frac{m a s s}{98}$

mass of H2SO4 = 0.0025 x 98 = 0.245g.

Read lesson note on Solubility Of Substances (Ghana Only) (WAEC)

Read lesson note on Acids, Bases And Salts (Ghana Only) (WAEC)

Solubility Of Substances (Ghana Only)

Acids, Bases And Salts (Ghana Only)

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