Chemistry Past Questions And Answers
Ethanol reacts with excess acidified K2Cr 2O7 to produce
- A. ethanal
- B. ethane
- C. ethanoic acid
- D. ethylethanoate
The number of molecules of Carbon(iv)Oxide produced when 10.0g of CaCO3 is treated with 0.2dm^3 of 1 Mole of HCL in the equation CaCO3 + 2HCL ⇒ CaCl2 + H2 O + CO2 , is ?
- A. 1.00 X 10^23
- B. 6.02 X 10^23
- C. 6.02 X 10^22
- D. 6.02 X 10^24
Which of the following metals cannot be extracted from its ore by using carbon or carbon (II) oxide as the reducing agent?
- A. Cu
- B.A1
- C. Zn
- D. Pb
The solubility of copper (II) tetraoxosulphate (Iv) is 75g in 100g of water at 100°C and 25g in 100g of water at 30°C. What mass of the salt would crystallize, if 50g of copper (II) tetraoxosulphate (VI) solution saturated at 100°C were cooled to 30°C ?
- A. 57.5
- B. 42.2
- C. 28.6
- D. 14.3
Which of the following types of bonding does not involve the formation of new substances?
- A) Metallic
- B) covalent
- C) co-ordinate
- D) electrovalent
The law of definite proportions states that
- A. pure samples of the same compound contain the same elements combined in the same proportion by mass
- B. pure samples of substances are in the same proportion by mass
- C. chemical compounds are pure because they contain the same elements
- D. matter can neither be created nor destroyed.
Dilute trioxonitrate (V) acid does not produce hydrogen when it reacts with metals because
- A. it reacts with the product.
- B. it is highly corrosive.
- C. there is no visible reaction.
- D. it is a strong oxidizing agent.
The indicator used in neutralizing CH3COOH and NaOH solution has pH range of
- A. 3-5
- B. 7-8
- C. 8-10
- D. 10-12
(a) Consider the following atoms: \(^R_T\)X; \(^S_T\)X.
(i) State the phenomenon exhibited by the two atoms.
(ii) What is the difference between the atoms?
(iii) Give two examples of elements that exhibit the phenomenon stated in (ai)
(iv) lf T is 17, write the electron configuration of the element
(b)(i) State two differences between metals and-non-metals with respect to their:
I. physical properties;
2. chemical properties.
(ii) Give one example of each for the following compounds:
I. an amphoteric oxide;
II. a hydride which evolves hydrogen when reacted with water;
Ill. a trioxocarbonate (IV) salt which is readily decomposed on heating;
IV. a chloride salt which is readily hydrolyzed in water.
(c)(i) State three characteristic properties of transition metals.
(ii) Write the electron configuration of \(_{30}Zn\)
(iii.) Explain briefly why zinc is not considered as a typical transition element.
(d) Consider the reaction represented by the following equation:- Na\(_2\)CO\(_{3(aq)}\) + MgCl\(_{2(aq)}\) ----> 2NaCl\(_{(aq)}\) + MgCO\(_{3(aq)}\). Calculate the mass of sodium trioxocarbonate (IV) needed to produce 3.36 of magnesium trioxocarbonate (IV). [C = 12.0, O = 16.0, Na = 23.0, Mg = 24:0 ]
Which of the following molecules is not linear in shape?
- A. CO2
- B. O2
- C. NH3
- D. HCI