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CBSE Class 9 Atoms and Molecules — practice questions — page 2

Explore 50 free Atoms and Molecules questions in CBSE Class 9 Science. Open each question or exercise to read its content, reference answers and available explanation.

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Atoms and Molecules questions and exercises with answers

Showing questions 31–50 of 50.

The water molecule is represented as:Read the answer and worked solution →CO2 is named:Read the answer and worked solution →Which prefix indicates four atoms?Read the answer and worked solution →CO is named carbon:Read the answer and worked solution →If 12 g of carbon combines with 32 g of oxygen, the carbon dioxide formed is:Read the answer and worked solution →Sodium chloride has sodium and chlorine in the mass ratio:Read the answer and worked solution →An atom with fewer than four valence electrons will usually:Read the answer and worked solution →Decomposing 9 g of pure water gives how much hydrogen?Read the answer and worked solution →Match the law or ideaRead the answer and worked solution →Element or compound molecule?Read the answer and worked solution →Sort the counting prefixesRead the answer and worked solution →True or false about atoms and moleculesRead the answer and worked solution →Numbers behind the lawsRead the answer and worked solution →Complete the bonding ruleRead the answer and worked solution →Spot the odd one outRead the answer and worked solution →Atomic foundations bingoRead the answer and worked solution →Match each fundamental chemical law with its scientific author and principle:Read the answer and worked solution →Match each mole concept quantity with its value or formula:Read the answer and worked solution →Match each polyatomic ion with its formula and valency:Read the answer and worked solution →Match each molecular compound with its correct molecular mass (in u):Read the answer and worked solution →

Worked practice questions

The water molecule is represented as:

  1. H2O
  2. HO2
  3. H3O
  4. HO3
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Correct answer: A. H2O

1. Oxygen needs two electrons and hydrogen needs one. 2. So two hydrogen atoms each share an electron with one oxygen. 3. The molecule is written H2O. 4. So the answer is H2O. _Source: syllabus Science, Ch 9 'Atomic Foundations of Matter'_

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CO2 is named:

  1. Carbon trioxide
  2. Carbon dioxide
  3. Carbon monoxide
  4. Carbon disulfide
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Correct answer: B. Carbon dioxide

1. The prefix shows how many atoms of the second element there are. 2. Two oxygen atoms take the prefix di. 3. So CO2 is named carbon dioxide. 4. The answer is carbon dioxide. _Source: syllabus Science, Ch 9 'Atomic Foundations of Matter'_

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Which prefix indicates four atoms?

  1. Hexa
  2. Mono
  3. Tetra
  4. Penta
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Correct answer: C. Tetra

1. Covalent compounds are named with counting prefixes. 2. Penta is five and hexa is six. 3. Tetra indicates four atoms. 4. So the answer is tetra. _Source: syllabus Science, Ch 9 'Atomic Foundations of Matter'_

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