Question Library

Rate of diffusion \(\frac{\alpha_1}{Density}\) or \(\frac{1}{\sqrt{Mm}}\) Rate = \(\frac{1}{time}\) \(\frac{1}{time}\) \(\frac{\alpha_1}{Density}\) or \(\frac{1}{\sqrt{Molarmass}}\) Time \(\alpha \sqrt{Density}\) or \(\sqrt{Molarmass}\) At constant volume of 100cm3 \(\frac{t_{o2}}{\sqrt{Mn_{o2}}}\) = \(\frac{t_{n2}}{\sqrt{1 \times 2}}\) \(\frac{50}{4 \sqrt{2}}\) = \(\frac{t_{n2}}{\sqrt{2}}\) tn2= 12.5s

Na is kept under kerosene (paraffin) to avoid reactivity with air. Paraffin is also known as Kerosene. Na(sodium) is kept in kerosene to prevent it from coming in contact with oxygen and moisture. If this happens, it will react with the moisture present in air and form sodium hydroxide.

Furring of kettles is caused by the temporary hardness in water. Temporary hardness in water is caused by calcium and magnesium trioxocarbonate (IV) CaCO3 causes the furring of kettles

Chlorine helps to keep water from germs and bacteria.

Balancing the chemical equation. Ca[OH]2 + 2NH4Cl → CaCl2 + 2H2O + 2NH3 X = NH3

\DeltaG= \DeltaH − T\DeltaS. To determine whether \DeltaG will be positive or negative, the value of \DeltaH(change in enthalpy) and \DeltaS (change in entropy) must be given. Likewise the temperature. Entropy represents the degree of disorder in a system. In a gaseous reaction, this is determined by the change in the number of moles of gas. Reactants: 1 mole of X + 3 moles of Y = 4 moles of gas Products: 2 moles of Z = 2 moles of gas. The spontaneity of a reaction is determined by the equation: \DeltaG= \DeltaH − T\DeltaS. \DeltaH is positive , T = is always positive, \DeltaS = is negative. Substituting the signs into the equation: \DeltaG= \DeltaH − T\DeltaS = (+) - (T x (-)) = + Since both terms are positive, \DeltaG must be positive regardless of the specific value of T as long as T is expressed in Kelvin (which is always > 0). A positive \DeltaG indicates the reaction is non-spontaneous at room temperature.

In the reactant; Cu\(_2\)S 2 Cu - 2(1) = 0 2 Cu = 2 Cu = \(\frac{2}{2}\) Cu = +1 In the product, Cu Cu = O (Oxidation state of an element in its free state is 0) The oxidation number of Cu in Cu\(_2\)S and Cu respectively is +1 and 0 respectively

The setup represents the production of sulfur dioxide. And the cylinder marked X is SO2

In the preparation of sulphur dioxide by the action of dilute acids on sulphates and bisulphites. conc H2SO4 helps to release SO2 from the mixture. The setup represents the production of sulphur dioxide

M = \(\frac{\text{Molar mass × Quantity of Electricity}}{\text{96500 × no of charge}}\) = \(\frac{MmIT}{96500n}\) Copper II Chloride = CuCl2 CuCl2 → Cu2+ + 2Cl2 Mass of compound deposited = \(\frac{\text{Molar mass × Quantity of Electricity}}{\text{96500 × no of charge}}\) Q = IT I = 0.5A T = 45 × 60 T = 2700s Q = 0.5 × 2700 = 1350c Molarmass = 64gmol-1 no of charge = + 2 Mass = \(\frac{64 \times 1350}{96500 \times 2}\) Mass = 0.448g

CH2CH2 - CCH3CH2 Start the numbering from the terminal carbon.

An element's chemical properties depend on its valence electrons.The chemical properties of elements depend on an element's electron configuration.

Test tubes are convenient containers for heating small amounts of liquids or solids with a Bunsen burner or alcohol burner.

Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers.

Scandium has electronic configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{1}4s^{2}\) hence, \(Sc^{3+}\) has configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}\). Hence, no electron in the 3d-orbital.