Atoms and Molecules (9 Science)
Atoms are the smallest indivisible particles of matter, while molecules are formed when two or more atoms combine chemically. This chapter explores the fun
TL;DR: Atoms are the smallest indivisible particles of matter, while molecules are formed when two or more atoms combine chemically. This chapter explores th…
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Atoms are the smallest indivisible particles of matter, while molecules are formed when two or more atoms combine chemically. This chapter explores the fun
Atoms and Molecules MCQs with Answers & Explanations
Q1. What is the atomic mass unit (amu) approximately equal to?
- 1/12th of carbon-12 atom ✓ (correct)
- 1/16th of oxygen atom
- Mass of one electron
- Mass of one proton
Q2. Which of the following has the smallest mass?
- Proton
- Neutron
- Electron ✓ (correct)
- Alpha particle
Q3. What is Avogadro's number?
- 6.02 × 10^23 ✓ (correct)
- 6.02 × 10^22
- 6.02 × 10^24
- 6.02 × 10^21
Q4. The molecular mass of CO2 is (C=12, O=16):
- 28
- 44 ✓ (correct)
- 36
- 32
Q5. How many atoms are present in one molecule of H2SO4?
- 5
- 6
- 7 ✓ (correct)
- 8
Q6. Which compound has the empirical formula CH and molecular mass 78?
- C6H6 ✓ (correct)
- C5H5
- C4H4
- C3H3
Q7. The mass of 0.5 mole of oxygen (O2) is (O=16):
- 8 g
- 16 g ✓ (correct)
- 32 g
- 64 g
Q8. Number of molecules in 11.2 L of CO2 at STP is:
- 3.011 × 10^23
- 6.022 × 10^23
- 1.505 × 10^23 ✓ (correct)
- 9.033 × 10^23
Q9. Which of the following has the highest molecular mass?
- CO2 ✓ (correct)
- H2O
- NH3
- CH4
Q10. The number of atoms in 2 moles of chlorine (Cl2) is:
- 6.022 × 10^23
- 12.044 × 10^23
- 2.411 × 10^24 ✓ (correct)
- 3.011 × 10^23
Frequently Asked Questions
What is the difference between atomic mass and atomic number?
Atomic number is the number of protons in an atom and determines the element's identity. Atomic mass is the sum of protons and neutrons (mass number) and determines the isotope.
Why is the mole concept important in chemistry?
The mole concept provides a bridge between the macroscopic world (grams we can measure) and the microscopic world (atoms and molecules), making calculations involving large numbers of particles manageable.
More 9 Science MCQs
- Light Reflection and Refraction
- Electricity
- Acids Bases and Salts
- Life Processes
- Carbon and its Compounds
- Metals and Non-metals
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