Writing Chemical FormulaePractice Questions & MCQs
Practice Writing Chemical Formulae questions from Atoms and Molecules (Class 9 Science) - important MCQs with answers and step-by-step solutions. Solve the sample questions below, then practice the full set free on the RankByte app.
Writing Chemical FormulaeQuiz - Solve & Score
Q1. A chemist drops sodium into a flask rich in chloride ions; using the criss-cross method, what formula does the salt that settles take?
- A.NaCl
- B.Na2Cl2
- C.Na2Cl
- D.NaCl2
Answer: A. NaCl
Sodium has valency 1 and chloride has valency 1. Criss-crossing gives sodium subscript 1 and chloride subscript 1, reduced to NaCl.
Q2. Heated in air, a strip of magnesium grabs oxide and turns into a powdery solid; what chemical formula describes that product?
- A.MgO2
- B.Mg2O
- C.MgO
- D.Mg2O2
Answer: C. MgO
Magnesium has valency 2 and oxide has valency 2. Criss-crossing gives magnesium subscript 1 and oxide subscript 1, reduced to MgO.
Q3. On a worksheet a learner must marry aluminium (valency 3) to oxide (valency 2); which formula belongs in the answer box?
- A.Al3O2
- B.Al3O3
- C.Al2O3
- D.AlO
Answer: C. Al2O3
Aluminium has valency 3 and oxide has valency 2. Criss-crossing gives aluminium subscript 2 and oxide subscript 3, reduced to Al2O3.
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Get early accessWriting Chemical Formulae - Frequently asked questions
Where can I practise Writing Chemical Formulae questions for Class 9 Science?
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Are these Writing Chemical Formulae questions important for the exam?
Yes. These Writing Chemical Formulae important questions follow the Science exam pattern (CBSE Boards, plus JEE and NEET foundation), so they help with both school and competitive prep.
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Every Writing Chemical Formulae question on RankByte comes with the correct answer and a full step-by-step solution, so you learn the concept instead of just guessing.