4th Dimension
5th - 12th ( Maths I Physics I Chemistry I Biology and Commerce) I IIT-JEE I NEET I KVPY I NTSE I Olympiads
I CBSE/ICSE/ISC/MP Boards Mob: 7999525079 - 7869709458
Test / Exam Name: Atoms And Molecules Standard: 9th Subject: Science
Student Name: Section: Roll No.:
Questions: 20 Time: 01:00 hh:mm Marks: 64
Q1. The mass of one atom of an element X is 2.0 × 10-23g. 4 Marks
1. Calculate the atomic mass of element X.
2. What could element X be?
Q2. The mass of one molecule of a substance is 4.65 × 10-23g. What is its molecular mass? What could this substance be? 4 Marks
Q3. Which has more number of atoms? 4 Marks
100g of N2 or 100g of NH3
Q4. Which contains more molecules, 10g of sulphur dioxide (SO2) or 10g of oxygen (O2)? 4 Marks
(Atomic masses: S = 32u; O = 16u)
Q5. State the law of conservation of mass. Give one example to illustrate this law. 4 Marks
Q6. What weight of oxygen gas will contain the same number of molecules as 56g of nitrogen gas? 4 Marks
(O = 16u; N = 14u)
Q7. Write the formulae of the following compounds. Also name the elements present in them. 4 Marks
1. Water.
2. Ammonia.
3. Methane.
4. Sulphur dioxide.
5. Ethanol.
Q8. An element A forms an oxide A2O5. 3 Marks
1. What is the valency of element A?
2. What will be the formula of chloride of A?
Q9. Identify the total number of inert gases, their names and symbols from this cross word puzzle. 3 Marks
Q10. Write the molecular formulae of all the compounds that can be formed by the combination of following ions. 3 Marks
Cu2+ , Na+ , Fe3+ , CL− , SO2−
4 , PO4
3−
Q11. Write the chemical formulae of Nitrates (NO3–) of Na+, K+, Al3+, Mg2+, Ca2+, Zn2+. 3 Marks
Q12. Give the formulae of the compounds formed from the following sets of elements. 3 Marks
1. Calcium and fluorine.
2. Hydrogen and sulphur.
3. Nitrogen and hydrogen.
4. Carbon and chlorine.
5. Sodium and oxygen.
6. Carbon and oxygen.
Q13. Calculate the molecular masses of the following: 3 Marks
1. Hydrogen, H2
2. Oxygen, O2
3. Chlorine, Cl2
4. Ammonia, NH3
5. Carbon dioxide, CO2
(Atomic masses: H = 1 u; O = 16 u; Cl = 35.5 u; N = 14 u; C = 12 u)
Q14. Calculate the molecular masses of the following compounds: 3 Marks
1. Methane, CH4
2. Ethane, C2 H6
3. Ethene, C2 H4
4. Ethyne, C2 H2
(Atomic masses: C = 12u; H = 1u)
Q15. You are provided with a fine white coloured powder which is either sugar or salt. How would you identify it without testing? 3 Marks
Q16. How are given mass, molar mass and number of moles related to each other? 3 Marks
Q17. Show by means of calculations that 5 moles of CO2 and 5 moles of H2O do not have the same mass. How much is the difference 3 Marks
in their masses?
Q18. Write the cations and anions present (if any) in the following compounds. 2 Marks
1. CH3COONa
2. NaCI
3. H2
4. NH4N03
Q19. If 6g of oxygen contains 1 mole of oxygen atoms, calculate the mass of one atom of oxygen. 2 Marks
Q20. What is the atomicity of the following? 2 Marks
1. Oxygen
2. Ozone
3. Neon
4. Sulphur
5. Phosphorus
6. Sodium
