The electronic configuration of an element is 1S2 2S2 2P6 3S2 3P3. How many unpaired electrons are there in the element?
A 5
B 4
C 3
D 2
Answer : C
Based on Hund’s rule, there are 3 unpaired electrons in the 3P3
Which of the following can be obtained by fractional distillation?
A. Nitrogen from liquid air
B. Sodium Chloride from sea water
C. Iodine from solution of Iodine in carbon tetrachloride
D. Sulphur from the solution of sulphur in carbon disulphide
Answer : A
The Fractional Distillation of Liquid Air
An air separation unit is often called an oxygen or nitrogen generator since its purpose is to extract one or both of these elements from the air. In the distillation process, the air is first passed through a filter that absorbs all the water vapour.
An air separation plant separates atmospheric air into its primary components, typically nitrogen and oxygen, and sometimes also argon and other rare inert gases. The most common method for air separation is fractional distillation.
Duralumin consists of aluminum, copper?
A. Zinc and Gold
B. Lead and Manganese
C. Nickel and Silver
D. Manganese and Magnesium
Answer: D
Duralumin is an alloy made up of 90% aluminium, 4% copper, 0.51% magnesium, and less than 1% manganese.
An example of a polysaccharide is?
A. Dextrose
B. Mannose
C. Glucose
D. Starch
Answer: D
A polysaccharide is a large molecule made of many smaller monosaccharides. Monosaccharides are simple sugars, like glucose. Enzymes bind these small monomers together creating large sugar polymers, or polysaccharides.
8g of CH4 occupies 11.2 at S.T.P. What volume would 22g of CH3CH2CH3 occupy under the same condition?
A. 3.7dm3
B. 11.2dm3
C. 22.4dm3
D. 33dm3
Answer: B
Molar mass of methane, CH4 = 16g/mol
At standard conditions, S.T.P., 8g CH4 occupies 11.2
then, 16g occupies 22.4 dm3
Molar mass of propane = 44g/mol-1 occupies 22.4dm3 at S.T.P
Then, 22g will occupy 11.2dm3
The best treatment for a student who accidentally poured conc tetraoxosulphate(vi) on his skin in the laboratory is to wash his skin with?
A. with cool running water
B. sodium hydroxide solution
C. iodine solution
D. sodium trioxonitrate(v) solution
Answer: A
Warning: Don’t try to neutralize the burn with acid or alkali. This could cause a chemical reaction that worsens the burn!
Which of the gas laws does this graph illustrate?
A. Boyle
B. Charles
C. Gay-Lussac
D. Graham
Answer: B
Charles’ law states that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature, if the pressure remains constant.
What are the possible oxidation numbers of an element if its atomic number is 17?
A. -1 and 7
B. -1 and 6
C. -3 and 5
D. -2 and 6
Answer: A
The element with atomic number 17 is Chlorine which has a valency of -1.
What process would coal undergo to give coal gas, coal tar, ammoniacal liquor and coke?
A. Steam distillation
B. Destructive distillation
C. Liquefication
D. Hydrolysis
Answer: B
Destructive distillation is a chemical process in which decomposition of unprocessed material is achieved by heating it to a high temperature; the term generally applies to the processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents, such as steam or phenols.
Liquid black soap is made by boiling palm oil with liquid extract of ash. The function of the ash is to provide the ?
A. Acid
B. Ester of alkanoic acid
C. Alkali
D. Alkanol
Answer: C
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations Na⁺ and hydroxide anions OH⁻
When water drops are added to calcium carbide in a container and the gas produced is passed through a jet and lighted, the resultant flame is called an?
A. Oxyethene
B. Oxyhydrocarbon flame
C. Oxyacetylene flame
D. Oxymethane flame
Answer: C
The reaction of calcium carbide with water, producing acetylene and calcium hydroxide. It is the major industrial use of calcium carbide.
Which of the following substances is a mixture?
A. Granulated sugar
B. Seawater
C. Sodium chloride
D. Iron filling
Answer : B
In chemistry, a mixture is a material made up of two or more different substances which are not chemically combined.
If the quantity of oxygen occupying 2.76L container at a pressure of 0.825 atm and 300k is reduced by one-half, what is the pressure exerted by the remaining gas?
A. 1.650atm
B. 0.825atm
C. 0.413atm
D. 0.275atm
Correct Option: A
Solution
By applying the combined gas law formula,
Given:
P1 = 0.825, V1 = 2.76 L, V2 = 1.38 L, P2 = ?
T1 = T2; we would have P2 = [ P1 X V1 ] ÷ V2
[0.825 X 2.76] ÷ 1.38
= 1.650atm
Four elements P, Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively. Which of these elements is noble gas?
A. P
B. Q
C. R
D. S
Answer: B
They are the most stable because they have the maximum number of valence electrons in their outer shell
The products of the thermal decomposition of ammonium trioxonitrate(v) are?
A. Nitrogen (I) Oxide and Water
B. Ammonia and Oxide
C. Nitrogen and Water
D. Nitrogen (IV) Oxide and Water
Answer: A
NH4NO3 Ammonium Trioxonitrate(V) decomposes on heating to give nitrogen(i)oxide N2O and water, unlike all other metallic trioxonitrates(v).How many valence electrons are contained in the element 31/15P ?
A. 3
B. 4
C. 15
D. 31
Answer: A
The element is Phosphorus in group 5 with valencies of 3 and 5. These are contained in the third energy level of the atom. Due to the number of valence electrons, Phosphorus is capable of forming three bonds with other elements.
Answer: C
The volume occupied by 1.58g of a gas at S.T.P is 500cm3. What is the relative molecular mass of the gas? [ G.M.V at S.T.P = 22.4dm23 ]
A. 28
B. 32
C. 44
D. 74
Answer: D
500cm3 of the gas weighed 1.58
22400cm3 of the gas weight:
[22400 X 1.58g] ÷ [ 500 ]
= 74
Which of the following gases will rekindle a brightly splint?
A. NO2
B. NO
C. N2O
D. CL2
Answer: C
The shape of ammonia molecule is?
A. Trigonal planar
B. Octahedral
C. Square planar
D. Tetrahedral
Answer: A
The ammonia molecule has a trigonal pyramidal shape with three hydrogen atoms and an unshared pair of electrons attached to the nitrogen atom.
Answer: A
HCL is very acidic . The addition of conc HCL makes the solution more acidic and the solution falls below the original value
Chromatography is used to separate components of mixture which differ in their rates of ?
A. diffusion
B. migration
C. reaction
D. sedimentation
Answer: B
Chromatography is a method of separating mixtures by using a moving solvent on filter paper.
Deliquescent substances are also?
A. efflorescent
B. anhydrous
C. hygroscopic
D. insoluble
Answer: C
Deliquescence is the process by which a substance absorbs moisture from the atmosphere until it dissolves in the absorbed water and forms a solution
Helium is used in observation of ballons because it is?
A. Light and combustible
B. light and non-combustible
C. heavy and combustible
D. heavy and non-combustible
Answer: B
Answer: B
32g of CUSO4 liberate 13.0kj of heat Molar mass of CUSO4 = 160g No. of moles of CUSO4 = 32g No. of moles = 32(mass) / 160(molar mass) = 0.2 moles i.e 0.2 = 13kj 1 moles = xkj 65KJAnswer: C
| M | Cl | |
| % composition | 20.22 | 79.78 |
| Atomic mass | 27 | 35.5 |
| Mole ratio | 20.22 | 79.78 |
| 27 | 35.5 | |
| 0.75 | 2.25 | |
| Divided | 0.75 | 0.75 |
| 1 | 3 |
What quantity of electricity will liberate 0.125 mole of oxygen molecules during the electrolysis of dilute sodium chloride solution?
A. 24,125 C
B. 48,250 C
C. 72,375 C
D. 96,500 C
Answer: B
4OH ⇒ 2H2O + O2 + 4e- …….. (i)
From equation (i):
1 mole of Oxygen requires 4e
i.e 1 mole of Oxygen requires 4F,
where 1F = 96,500 C
[ 4 X 96,500 X 0.125 ] ÷ 1
= 48,250 C
Which of the following types of bonding does not involve the formation of new substances?
A. Metallic
B. Covalent
C. Co-ordinate
D. Electrovalent
Answer: A
An organic compound that does not undergo a reaction with both hydrogen cyanide and hydroxylamine can be?
A. Alkene
B. Alkanal
C. Alkanone
D. Alkanoic Acid
Answer: C
The substance often used for vulcanization of rubber is?
A. Chlorine
B. Hydrogen peroxide
C. Sulphur
D. Tetraoxosulphate(vi) acid
Answer : C
Vulcanization of rubber is among the several uses of sulfur
The chlorinated alkane often used industrially to remove grease is?
A. Tetrachloromethane
B. Chloromethane
C. Trichloromethane
D. Dichloromethane
Answer: A
Tetrachloromethane is an effective solvent within the chemical industry and is used to clean machinery and electrical equipment.
What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen?
A. 8.0g
B. 16.0g
C. 36.0g
D. 72.0g
Answer: D
2H2 + O2 ⇒ 2H2O From the equation: 4g of Hydrogen produces 36g of water 8g of Hydrogen will produce 72g of waterProteins in acid solution undergo?
A. Substitution
B. Fermentation
C. Hydrolysis
D. Polymerisation
Answer: C
Acid hydrolysis refers to a hydrolysis reaction occurring under acidic conditions. Acid hydrolysis of a protein breaks the polymer down into its constituent amino acids.
The general formula for the Alkanals is?
A. R2CO
B. RCHO
C. ROH
D. RCOOR
Answer: B
Alkanals (Aldehydes) have the general formula RCHO
Where R and R’ may be alkyl or aryl groups.
When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes?
A. Bipolar
B. Negatively charged
C. Positively charged
D. Neutral
Answer: C
When these cathode rays are deflected onto an electrode of an electrometer, the instrument measured a negative charge.
When a solid substance disappears completely as a gas on heating, the substance is said to have undergone?
A. Sublimation
B. Crystallization
C. Distillation
D. Evaporation
Answer: A
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state
An electron can be added to a halogen atom to form a halide ion with?
A. 8 valence electrons
B. 7 valence electrons
C. 2 valence electrons
D. 3 valence electrons
Answer: A
A halide ion is a halogen atom bearing a negative charge. eg : (F−), chloride (Cl−), bromide (Br−), iodide (I−)
Aluminum hydroxide is used in the dyeing industry as a?
A. Dye
B. Dispersant
C. Salt
D. Mordant
Anwer: D
Aluminium hydroxide, Al(OH)₃ is used as a mordant in dyeing.
The most important element on the earth’s crust is?
A. Nitrogen
B. Hydrogen
C. Oxygen
D. Fluorine
Answer: C
Earth’s crust is made up of several elements: oxygen, 46.6% by weight; silicon, 27.7%; aluminum, 8.1%; iron, 5%; calcium, 3.6%; sodium, 2.8%, potassium, 2.6%, and magnesium, 2.1%.
To obtain pure carbon(ii)oxide from its mixture with carbon(iv)oxide, the mixture should be?
A. Passed over heated copper(ii)oxide
B. Bubbled through water
C. Bubbled through conc H2SO4
D. Bubbled through conc NAOH
Answer: D
