Filter by exam, subject and year then load questions instantly
Advertisement
post-utme2021chemistry
Q1. The gas which causes global warming is?
AO₂
BCO₂
CN₂
DHe
Correct Answer: B
Carbon dioxide (CO₂) is the primary greenhouse gas responsible for global warming. It traps heat from the sun in the earth's atmosphere by absorbing infrared radiation, preventing it from escaping into space. Human activities such as burning fossil fuels and deforestation increase CO₂ levels, intensifying the greenhouse effect.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q2. A solution contains 20g of solute in 180g of solvent. If the solvent is water, what is the concentration of the solution in terms of mass by mass percentage?
A11%
B22.20%
C10%
D20%
Correct Answer: C
Mass by mass percentage = (mass of solute ÷ total mass of solution) × 100. Total mass of solution = 20 + 180 = 200 g. Percentage = (20 ÷ 200) × 100 = 10%.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q3. The maximum number of electrons in the N shell is?
A2
B8
C18
D32
Correct Answer: D
The maximum number of electrons in any shell is given by the formula 2n², where n is the principal quantum number. For the N shell, n = 4. Maximum electrons = 2 × 4² = 2 × 16 = 32.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q4. One of the following is not a physical property of monosaccharides?
AMonosaccharides get charred when heated
BMonosaccharides are water-soluble, sweet substances
CThey are highly vital to the exploration of metals
DThey can be reduced to sugar alcohols
Correct Answer: C
Physical properties of monosaccharides include solubility in water, sweet taste, ability to char on heating, and reducibility to sugar alcohols (polyols). Being vital to the exploration of metals has no connection to monosaccharides and is not a physical property of them. This is the option that does not describe a property of monosaccharides.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q5. The atomic weight of nitrogen is?
A10
B12
C14
D16
Correct Answer: C
Nitrogen (N) has an atomic number of 7 and a relative atomic mass (atomic weight) of 14. This value reflects that the most abundant isotope of nitrogen is ¹⁴N, which contains 7 protons and 7 neutrons. Atomic weight 12 belongs to carbon, and 16 belongs to oxygen.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q6. The molar enthalpy change accompanying the removal of an electron from a gas phase atom or ion in its ground state is called?
AElectron gain enthalpy
BIonization enthalpy
CEnthalpy change
DEnthalpic gas removal
Correct Answer: B
Ionization enthalpy (ionization energy) is the energy required to remove one mole of electrons from one mole of gaseous atoms or ions in their ground state. The first ionization enthalpy removes the outermost electron. Electron gain enthalpy is the opposite process, involving the addition of an electron to a gaseous atom.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q7. The enzyme that converts glucose to ethyl alcohol is?
AMaltase
BZymase
CDiatase
DInvertase
Correct Answer: B
Zymase is the enzyme complex found in yeast that converts glucose directly into ethanol (ethyl alcohol) and carbon dioxide during fermentation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Maltase converts maltose to glucose, invertase converts sucrose to glucose and fructose, and diastase converts starch to maltose.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q8. A binary compound of oxygen with another element is referred to as?
AOxide
BElement
CCarbon
DNitrogen
Correct Answer: A
An oxide is a binary compound formed between oxygen and another element. Binary means it contains exactly two different elements, one of which is oxygen. Examples include water (H₂O), iron oxide (Fe₂O₃), carbon dioxide (CO₂), and sodium oxide (Na₂O). All these are classified as oxides.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q9. The process by which salt and water react in a limited way to form an acid or a base is?
ANeutral process
BBasic acidic process
CHydrolysis
DSublimation
Correct Answer: C
Salt hydrolysis is the reaction of a salt with water to produce an acidic or basic solution. When a salt of a weak acid and strong base dissolves in water, the anion reacts with water to produce a basic solution. When a salt of a strong acid and weak base dissolves, the cation reacts with water to produce an acidic solution. This process is called hydrolysis.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q10. The mass number of a nucleus is?
AAlways less than its atomic number
BThe sum of the number of protons and neutrons present in the nucleus
CAlways more than the atomic weight
DA fraction
Correct Answer: B
The mass number (A) of an atom is defined as the total number of nucleons (protons and neutrons) in the nucleus. Mass number = number of protons + number of neutrons. It is always a whole number. The atomic number is only the number of protons, and the atomic weight is an average that may be a decimal due to isotopes.
Generating AI explanation...
AI Explanation
post-utme2021chemistry
Q11. A sample of any of the following substances disappears after some time when exposed to air like camphor, naphthalene, or dry ice. This phenomenon is called?
ASublimation
BEvaporation
CDiffusion
DRadiation
Correct Answer: A
Sublimation is the direct conversion of a solid into vapour without passing through the liquid state. Camphor, naphthalene, and dry ice (solid CO₂) all sublime at room conditions, gradually disappearing as they convert directly from solid to gas. Evaporation applies to liquids, not solids.