Sample Chemistry Questions
Q1: What is the atomic number of Carbon?
Q2: Which type of bond involves the sharing of electron pairs between atoms?
A. Ionic bond
B. Metallic bond
C. Covalent bond ✓
D. Hydrogen bond
Q3: How many moles are in 44 grams of CO₂ (molar mass 44 g/mol)?
A. 0.5 mol
B. 1 mol ✓
C. 2 mol
D. 44 mol
📖 Study Tips for Chemistry
1
Memorize the first 20 elements of the periodic table along with their symbols, atomic numbers, and common valences.
2
Balance chemical equations by adjusting coefficients, never subscripts — changing subscripts changes the substance entirely.
3
Understand electron configuration (especially the octet rule and exceptions like H, He, and transition metals) before studying bonding.
4
For stoichiometry, always convert to moles first; the mole is the central unit that connects mass, volume, and number of particles.
❓ Chemistry FAQ
What is the difference between an ionic and covalent bond?
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An ionic bond forms when one atom transfers electrons to another (typically between a metal and nonmetal), creating oppositely charged ions that attract. A covalent bond forms when two atoms share electrons (typically between two nonmetals).
What is a mole in chemistry?
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A mole is 6.022 × 10²³ particles (Avogadro's number). It is the SI unit of amount of substance and lets chemists count atoms and molecules by weighing them. One mole of any element equals its molar mass in grams.
What is the difference between exothermic and endothermic reactions?
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Exothermic reactions release energy (heat flows out, products are lower energy than reactants). Endothermic reactions absorb energy (heat flows in, products are higher energy). Combustion is exothermic; dissolving ammonium nitrate is endothermic.
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