Class 9 Science MCQ Questions Structure of the Atom with Answers

Welcome to StudyMats. This comprehensive educational guide for Class 9 Science MCQ Questions Structure of the Atom with Answers is prepared to assist students in preparing effectively for their school, board, and competitive examinations. All questions, exercise solutions, and concept notes strictly adhere to the latest NCERT curriculum and CBSE guidelines.

📖 Curriculum: NCERT / CBSE Latest Syllabus  |  🎯 Focus: Conceptual Clarity & Board Exam Success

MCQ Questions for Class 9 Science Chapter 4 Structure of the Atom with Answers

Q1. Which of the following has largest number of particles?
8g of `CH_{4}`
4.4g of `CO_{2}`
 34.2g of `C_{12}H_{22}C_{11}`
2g of `H_{2}`

---

Q2. The number of molecules in 16.0g of oxygen is:
6.02 `\times 10^{23}`
6.02 `\times 10^{-23}`
3.01 `\times 10^{-23}`
3.01 `\times 10^{23}`

---

Q3. The percentage of hydrogen in `\H_{2}`O is
8.88
11.12
20.60
80.0

---

Q4. Find the mass of oxygen contained in 1 kg of potassium nitrate `\KNO_{3}`
475.5g
485.5g
475.2g
485.2g    

---

Q5. How many moles of electron weight one kilogram?
6.023 `\times 10^{23}`
6.023 `\times 10^{8}`
9.108 `\times 10^{54}`

1.82 `\times 10^{8}`

---

Q6. 25.4g of iodine and 14.2g of chlorine are made to react completely to yield a mixture of `\ICl` and `\ICl_{3}`. Calculate the ratio of moles of `\ICl` and `\ICl_{3}`

1:1
2:1
3:1
1:2

---

Q7. The mass of sodium in 11.7 g of sodium chloride is:
2.3g
4.6g
6.9g
7.1g

---

Q8. The formula of a chloride of a metal M is `\MCl_{3}`. The formula of the phosphate of metal M will be:
`\MPO_{4}`
`\M_{2}PO_{4}`
`\M_{3}PO_{4}`
`\M_{2}(PO_{4})_{3}`

---

Q9. Which of the following contains the largest number of molecules?
0.2 mol 0f `\H_{2}`
8.0 g of `\H_{2}`
17 g of `\H_{2}O`
6.0 g of `\CO_{2}`

---

Q10. One gram of which of the following contains largest number of oxygen atoms?
`\O`
`\O_{2}`
`\O_{3}`
All contain same

---

Q11. The percentage by weight of `\O_{2}` in `\CaSO_{4}` (O = 16, S = 32, Ca = 40) is:
64
28.2
47.2
16.2

---

Q12. The percentage by weight of Zn in white vitriol, `\ZnSO_{4}.7H_{2}O` (Zn = 65, S = 32. O = 16, H = 1) is approximately:
23
33
43
13

---

Q13. The formation of `\SO_{2}` and `\SO_{3}` explain:
The law of conservation of mass
The law of multiple proportions
The law of definite properties
Boyle's law

---

Q14. The law of definite proportions was given by:
John Dalton
Humphry davy
Proust
Michael Faraday

---

Q15. Molecular mass is defined as the:
Mass of one atom compared with the mass of one molecule
Mass f one atom compared with the mass of one atom of hydrogen
Mass of one molecule of any substance compared with the mass of one atom of C – 12
None of the above

---

Q16. 0.001 g of C is required t write a letter with a graphite pencil. The total number of C atoms used in writing the letter is:
5.00 `\times 10^{12}`
5 `\times 10^{19}`
5.0 `\times 10^{24}`
6.023 `\times 10^{23}`

---

Q17. One mole of a gas occupies a volume of 22.4 L. This is derived from:
Berzelius’s hypothesis
Gay- Lussac’s law
Avogadro’s law
Dalton’s law

---

Q18. The mass of one C atom is:
6.023 `\times 10^{23}`
1.99 `\times 10^{-23}`
2.00 g
12 g

---

Q19. The chemical symbol for barium is:
B
Ba
Be
Bi

---

Q20. The chemical symbol P stands for:
Phosphorus
Potassium
Polonium
Promethium

---

Q1. D	Q2. D	Q3. B	Q4. B
Q5. D	Q6. A	Q7. B	Q8. A
Q9. B	Q10. C	Q11. C	Q12. A
Q13. B	Q14. C	Q15. C	Q16. B
Q17. C	Q18. B	Q19. B	Q20. A

---

Q1. A group of atoms chemically bonded together is a (an):
Molecule
On
Salt
Element

---

Q2. Adding electrons to an atom will result in a (an):
Molecule
Cation
Salt

---

Q3. When an atom loses electrons, it is called a (an) ______ and has a _____ charge.
Anion, positive
Cation, positive
Anion, negative
Cation, negative

---

Q4. The molecule formula `\P_{2}O_{5}` means that:
A molecule contains 2 atoms of P and 5 atoms of O
The ratio of the mass of P to the mass of O in the molecule is 2:5
There are twice as many P atoms in the molecule as there are O atoms
The ratio of the mass of P to the ass of O in the molecule is 5:2

---

Q5. The correct symbol for silver is:
Ag
S
Ar
Ai

---

Q6. A spartame, an artificial sweetener, has the molecular formula  `\C_{14}H_{18}N_{2}O_{5}`. What is the mass in grams of one molecule? (Atomic weights: C = 12.01, H = 1.008, N = 14.01, O = 16.00)
`\4.89 times 10^{-21}`
`\2.24 times 10^{-21}`
`\3.85 times 10^{-22}`
`\4.89 times 10^{-22}`      

---

Q7. Morphine, an addictive drug, has the molecular formula  `\C_{17}H_{19}NO_{3}`. What is the mass in grams of one molecule?(Atomic weights: C = 12.01, H = 1.008, N = 14..1, O = 16.00)
`\2.24 times 10^{-22}`
`\3.85 times 10^{-22}`
`\3.85 times 10^{-21}`
`\4.74 times 10^{-22}`      

---

Q8. The controversial artificial sweetener saccharin has the molecular formula  `\C_{3}H_{5}O_{5}NS`. What is the mass in grams of one molecule? Atomic weights: C = 12.01, H = 1.008, O = 16.00, N = 14.01, S = 32.06.
`\5.55 times 10^{-21}`  
`\3.85 times 10^{-22}`  
`\2.24 times 10^{-22}`  
`\2.24 times 10^{-21}`  

---

Q9. The statue of Liberty is made of 2.0 x 105 Ibs of copper sheets bolted to a framework. (1Ib = 454 g) . How many atoms of copper are on the statue? (Atomic weight: Cu = 63.5.)
`\2.1 times 10^{27}` 
`\8.6 times 10^{29}` 
`\4.3 times 10^{26}` 
`\8.6 times 10^{26}`       

---

Q10. Selenium ingested in the amount of 90 micrograms per day causes loss of hair. How many selenium atoms are in this size sample? (Atomic weight: Se = 78.96.)
`\6.9 times 10^{23}` 
`\8.8 times 10^{17}` 
`\8.8 times 10^{22}` 
`\6.9 times 10^{17}`   

---

Q11. Novocain is  `\C_{13}H_{16}N_{2}O_{2}. What is the total number of moles of atoms in 0.020 moles of Novocain? (Atomic weights: C = 12.01, O = 16.00, N = 14.01, H = 1.008.)
0.033
3.3
0.66
0.33

---

Q12. Methoxychlor, a garden insecticide, has the molecular formula  `\C_{16}H_{15}C_{13}O`. What is the total number of moles of atoms in a 3.0 mg sample? (Atomic weights: C = 12.01, H = 1.008, Cl = 35.45, O = 16.00)
`\8.7 times 10^{-6}` 
`\3.0 times 10^{-5}` 
`\3.1 times 10^{-1}` 
`\3.1 times 10^{-4}`   

---

Q13. What are the total number of moles of atoms in 4.32 g of  `\Sc(NO_{3})_{3}?(Atomic weights: Sc = 45.0, O = 16.00, N = 14.01.)
0.0132
0.324
0.0187
0.243

---

Q14. Two samples of lead oxide were separately reduced to metallic lead by heating in a current of hydrogen. The weight of lead from one oxide was half the weight of lead obtained from the other oxide. The data illustrates:
Law of reciprocal proportions
Law of constant proportions
Law of multiple proportions
Law of equivalent proportions

---

Q15. The percentage of copper and oxygen in samples of CuO obtained by different methods were found to be the same. The illustrate the law of:
Constant proportion
Conservation of mass
Multiple proportions
Reciprocal proportions

---

Q16. The total number of atoms represented by the compound  `\CuSO_{4}.5H_{2}O is:
27
21
5
8

---

Q17. In compound A, 1.00g of nitrogen unites with 0.57 g of oxygen. In compound B, 2.00 g of nitrogen combines with 2.24g of oxygen. In compound C, 3.00g of nitrogen combines with 5.11g of oxygen. These results obey the following law:
Law of constant proportion
Law of multiple proportion
Law of reciprocal proportion
Dalton’s law of partial pressure

---

Q18. The weight of a molecule of the compound  `\C_{60}H_{122} is:
`\1.4 times 10^{-21} g` 
`\1.09 times 10^{-21} g` 
`\5.025 times 10^{23} g` 
`\16..023 times 10^{23} g`   

---

Q19. The mass of a molecule of water is:
`\3 times 10^{-26} Kg` 
`\3 times 10^{-25} Kg` 
`\1.5 times 10^{-26} Kg` 
`\2.5 times 10^{-26} Kg`   

---

Q20. The number of atom in 4.25g of  `\NH_{3}` is approximately:
`\1 times 10^{23} `
`\2 times 10^{23} `
`\4 times 10^{23} `
`\6 times 10^{23} `

---

Q1. A	Q2. B	Q3. B	Q4. A
Q5. A	Q6. D	Q7. D	Q8. C
Q9. B	Q10. D	Q11. C	Q12. D
Q13. D	Q14. C	Q15. A	Q16. B
Q17. B	Q18. A	Q19. A	Q20. D

---

Set 3 Update soon

Set 4 Update soon

Set 5 Update soon

Set 1 Set 2 set 3 Set 4 Set 5

💡 Important Exam & Study Tips

• Master NCERT Fundamentals: Ensure thorough familiarity with standard textbook definitions, formulas, and in-text examples before solving advanced problems.
• Step-by-Step Presentation: In board examinations, neat presentation, correct formula application, and labeled steps earn maximum step-marking.
• Practice Under Timed Conditions: Regular practice with previous years' question papers (PYQs) builds exam speed and accuracy.

📚 Related Study Materials on StudyMats

Access more chapter-wise notes and practice papers:

• StudyMats Home — Complete Educational Study Material
• Class 9 Science Study Notes & Question Papers

❓ Frequently Asked Questions (FAQs)

Q1: Are these solutions aligned with the latest rationalized syllabus?

Yes, all study notes and practice questions on StudyMats strictly follow the updated NCERT textbook pattern and CBSE assessment guidelines.

Q2: How can I prepare this chapter for highest marks?

Review the theory thoroughly, solve all textbook exercise questions, and repeatedly practice the high-frequency questions provided in this guide.