Chemistry MCQs
Topic Notes: Chemistry
MCQs and preparation resources for competitive exams, covering important concepts, past papers, and detailed explanations.
Plato
- Biography: Ancient Greek philosopher (427–347 BCE), student of Socrates and teacher of Aristotle, founder of the Academy in Athens.
- Important Ideas:
- Theory of Forms
- Philosopher-King
- Ideal State
1
For a reaction where ΔG = -45 kJ/mol and ΔH = -90 kJ/mol at 0°C (273 K), calculate the temperature at which the reaction becomes spontaneous.
Answer:
273 K
A reaction is spontaneous when ΔG < 0. Given ΔG = ΔH - TΔS, we first find ΔS at 273 K: -45 = -90 - 273(ΔS), so ΔS = -45/273. The reaction is spontaneous when ΔH < TΔS. At the equilibrium temperature (ΔG=0), T = ΔH/ΔS = -90 / (-45/273) = 546 K. However, since the reaction is already spontaneous at 273 K, it remains spontaneous at all temperatures below 546 K.
2
What is denoted by the subscript 'c' in Kc?
Answer:
molar concentration at equilibrium
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3
What is represented by each figure within a square bracket in the equilibrium expression?
Answer:
concentration in mol.dm-3
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4
At equilibrium, what is the relationship between the equilibrium constant (Kp) and the reaction quotient (Kc) for the reaction 2HI ____________> H2+ I2?
Answer:
Kp= kc
The correct answer is that the equilibrium constant (Kp) and reaction quotient (Kc) are equal for the reaction, indicating that the reaction is at equilibrium.
5
In the human diet, cellulose is referred to as
Answer:
fiber
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6
Vitamin B is necessary for
Answer:
energy production in cells
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7
Glyceryl esters or glycerides is another term for
Answer:
fats and oils
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8
For a reaction involving only gases at 25?C the equilibrium constant can be expressed in terms of molarity Ke or partial pressure Kp. Which is true about the numerical value of Kp ?
Answer:
Kc is equal to Kp if the total moles of reactants and products are equal
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9
What is formed when maltose undergoes hydrolysis?
Answer:
glucose and glucose
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10
Concentration of solute molecule when they are in equilibrium with solid substance at particular temperature is called________________?
Answer:
solubility
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