OAU POST UTME PRACTICE: Chemistry Quiz

The hybridization and bond angle of some covalent molecules are given below;

Which of the list is applicable to BF3 and BeCl2 respectively?

An element X, consisting of two isotopes of. mass numbers 35 and 37, has an atomic number 35.5. What is the relative abundance of the isotope of mass number 37

Consider the table below
Which of the options below identify method of preparation of i, ili and iv?

For the reaction
2H2(g) + 2NO(g) → N2(g) + 2H20(g)
the rate law is rate = k[H2)(NOJ2.
At a given temperature, what is the effect on the reaction rate if the concentration of H2 is doubled and the concentration of NO is halved?

In which of the following devices is nuclear fission applicable?
I. Atomic pile
II. Cathode ray tube
III. Hydrogen bomb
IV. Atomic bomb
V. Geiger Muller counter

A substance X can conduct electricity when in molten form but not when in solid form. X could be

The energy required to remove the most loosely bound electron from a gaseous atom to form a gaseous ion is

Consider the following chemical equations
Which of the numbered chemical species react like Lewis acid?

Calcium carbonate, CaCO, decomposes upon heating to calcium oxide and carbon dioxide.
What mass of solid calcium carbonate is required to produce 2.40 dm3 of carbon dioxide measured at STP? (GMV =22.4 dm3)

Which of the foliowing is a terminai aikyne?

What is the temperature at which the reaction below is at equilibrium?

Arrange the following gases in increasing order of diffusion rate: i. Helium ii. Methane iii. Nitrogen iv. Hydrogen sulphide

Which of the following combinations of cation and anion will produce an ionic compound with covalent character?

What is the standard cell potential for the reaction
2Cr + 3Sn2+ → 3Sn + 2Cr3+, given the E° values
shown
Cr3+ + 3e- → Cr, E° = -0.744V
Sn2+, + 2e- →Sn, E°= -0.141V

The solubility of calcium fluoride at 37°C is 3.9 gdm-3. What is the solubility product of the salt at this temperature? [Ca=40.0, F=19.0 gmol-1]

A tetraoxosulphate (vi) salt of iron is 24% sulphur by mass. What is the formular of the salt? [Fe = 56, S =32, 0 = 16]

The ions X- and Y+ are isoelectronic, each containing a total of 10 electrons. How many protons are in the nuclei of the neutral atoms of X and Y respectively

For the organic molecules:
(i) C4H10 (ii) C4H6 (iii) C4H8 (iv) C6H6 (v) C7H8
The double bond equivalents (DBEs) are respectively

Which of the following samples will react fastest with dilute trioxonitrate V acid

The sample of a radioactive element with a half life of 6hrs has an initial mass of 250g. Calculate the time it will take for the mass of the sample to remain 20g

If a mixture of 1.25 moles of nitrogen gas, 2.0 moles of oxygen gas and an unspecified amount of hydrogen gas sealed in a vessel at 25°C exerts a pressure of 9.6Nm? and the partial pressure of hydrogen is 2.35Nm-2, calculate the mass of hydrogen gas in the
mixture. (H = 1)

A choloform solution of a compound was spotted at a distance of 0.5cm from the base of a 10cm long chromatopaper. Upon dilution, the solvent front got to a place 0.25cm from the top of the chromatopaper. If the R, value of the compound is 0.72, what is the distance moved by the spot of the compound way up from the origin

Which of the following are reasons why reaction rates increase as temperature increases?
I. Collisions are more frequent between molecules at higher temperatures.
II. A greater fraction of collisions have sufficient energy to exceed Ea at higher temperatures.
III. Reactant concentrations are higher at higher temperatures.

For the reaction A + B → C. The rate is given as R = k[A]*[B]’ when the concentration of the reaction remains the same but when the concentration of B is doubled and that of A is constant, the rate quadruples.
The values of * and ‘ are respectively

When ammonium nitrate is dissolved in water

An aqueous solution of a substance turns acidification K2CrO, solution from orange to green. The aqueous solution also decolourises acidified KMn solution. It can therefore be inferred that the substance in the aqueous solution is

A compound C4H6 reacts with bromine and forms a white precipitate with ammoniacal silver nitrate solution. It reacts with dilute H2SO4 in the presence of mercuric sulphate to form 2 -butanone. The compound could be

Which of the following metals cannot be extracted by ordinary chemical reduction?

Which of the following oxides share a similar chemical property with oxygen?