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#1
By TheQuizWire
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Medium
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Fact Checked
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23 Jan 2026
If a fixed amount of ideal gas has its absolute temperature doubled and volume halved, what change occurs in its pressure?
💡 Explanation:This problem is solved using the Combined Gas Law, P1V1/T1 = P2V2/T2, for a fixed amount of gas (n is constant). If the absolute temperature (T) is doubled (T2 = 2T1) and the volume (V) is halved (V2 = 0.5V1), the final pressure (P2) is calculated as P2 = P1 <strong> (V1/V2) </strong> (T2/T1) = P1 <strong> (V1 / 0.5V1) </strong> (2T1 / T1) = P1 <strong> 2 </strong> 2 = 4P1. The pressure quadruples.
#2
By TheQuizWire
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Easy
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Fact Checked
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19 Jan 2026
What subatomic particle’s number uniquely defines an element and is its atomic number?
💡 Explanation:The atomic number (Z) of an element is defined by the number of protons in the nucleus. Changing the number of protons changes the element itself. The number of neutrons can change to form an isotope, and the number of electrons can change to form an ion, neither of which changes the fundamental identity (element) of the atom.
#3
By TheQuizWire
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Hard
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Fact Checked
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15 Jan 2026
Which factor allows polymerization, a process with negative entropy change ((Delta S < 0)), to be thermodynamically spontaneous?
💡 Explanation:The criterion for a spontaneous process is a negative change in Gibbs free energy ((Delta G < 0)), according to the equation (Delta G = Delta H - TDelta S). Polymerization is the linking of small monomers into a large polymer chain, which decreases the total number of free molecules, resulting in a negative entropy change ((Delta S < 0)). For the reaction to still be spontaneous ((Delta G < 0)), the enthalpy change ((Delta H)) must be highly negative (exothermic) to overcome the positive term of (-TDelta S), especially at lower temperatures where the spontaneity is often observed.
#4
By TheQuizWire
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Hard
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Fact Checked
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01 Jan 2026
Which periodic group element acts as a donor impurity to dope pure silicon?
💡 Explanation:Silicon is a Group 14 element (4 valence electrons). A donor impurity, which creates an n-type semiconductor, must be an element with five valence electrons, found in Group 15 (e.g., Phosphorus or Arsenic). The fifth valence electron is not required for bonding and is 'donated' to the conduction band.
#5
By TheQuizWire
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Medium
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Fact Checked
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25 Dec 2025
How many grams of $text{H}_2text{O}$ are produced by the complete combustion of 16g of $text{CH}_4$?
💡 Explanation:The balanced chemical equation for the complete combustion of methane is $text{CH}_4 + 2text{O}_2 rightarrow text{CO}_2 + 2text{H}_2text{O}$. The molar mass of methane ($text{CH}_4$) is approximately $16 text{ g/mol}$ and the molar mass of water ($text{H}_2text{O}$) is $18 text{ g/mol}$.
Step 1: Convert mass of $text{CH}_4$ to moles.
$text{Moles of } text{CH}_4 = text{Mass} / text{Molar Mass} = 16text{g} / 16 text{ g/mol} = 1 text{ mole}$.
Step 2: Use stoichiometry to find moles of $text{H}_2text{O}$.
The equation shows a $1:2$ mole ratio between $text{CH}_4$ and $text{H}_2text{O}$.
$text{Moles of } text{H}_2text{O} text{ produced} = 1 text{ mole } text{CH}_4 times (2 text{ moles } text{H}_2text{O} / 1 text{ mole } text{CH}_4) = 2 text{ moles}$.
Step 3: Convert moles of $text{H}_2text{O}$ to mass.
$text{Mass of } text{H}_2text{O} = text{Moles} times text{Molar Mass} = 2 text{ moles} times 18 text{ g/mol} = 36 text{ grams}$.
#6
By TheQuizWire
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Medium
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Fact Checked
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19 Dec 2025
For a gaseous reaction where $4$ moles of reactants yield $2$ moles of products, how does increased pressure shift equilibrium?
💡 Explanation:According to Le Chatelier's principle, increasing the pressure on a gaseous system at equilibrium will cause the system to shift towards the side with the fewer total moles of gas to counteract the stress. Since 4 moles (reactants) yield 2 moles (products), the shift favors the product side.
#7
By TheQuizWire
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Medium
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Fact Checked
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12 Dec 2025
A solution of hydrochloric acid has a pH of 3. What is the approximate new pH if diluted ten times?
💡 Explanation:A pH of 3 corresponds to a hydrogen ion concentration $([H^+]$) of $10^{-3} M$. Diluting the solution ten times reduces the concentration by a factor of 10. The new $[H^+]$ is $frac{10^{-3}}{10} = 10^{-4} M$. The new pH is calculated as $-log_{10}[H^+]$, which is $-log_{10}(10^{-4}) = 4$.
#8
By TheQuizWire
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Medium
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Fact Checked
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09 Dec 2025
What distinguishes isotopes of the same element?
💡 Explanation:Isotopes are atoms of the same element, meaning they have the same atomic number (number of protons). They are distinguished by having a different number of neutrons, which results in a different mass number.
#9
By TheQuizWire
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Medium
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16 Nov 2025
Which group of reactive metals is located in Column 1 of the periodic table?
💡 Explanation:Alkali metals (Group 1) are highly reactive elements that readily lose one electron to form cations.
#10
By TheQuizWire
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Medium
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09 Nov 2025
What is the term for a pure substance formed when two or more different chemical elements are chemically bonded together in fixed proportions?
💡 Explanation:A compound is a substance made up of two or more different elements chemically joined together. Unlike mixtures, compounds cannot be separated into simpler substances by physical means.
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