MCQ practice · SSC Chemistry Board questions · Chapter 6: Concept of Mole and Chemical Counting
How many atoms are there in one molecule of potassium dichromate?
Think it through first, then pick an option.
- a 7
- b 9
- c 11
- d 13
Answer and explanation
Correct answer: c 11
K₂Cr₂O₇: 2 K + 2 Cr + 7 O = 11 atoms.
Why the other options are wrong
- a 7: 7 counts only the O atoms; K₂Cr₂O₇ has 2 + 2 + 7 = 11.
- b 9: 9 leaves the Cr out (2 K + 7 O); the right count is 2 + 2 + 7 = 11.
- d 13: Not 13; K₂Cr₂O₇ has 2 + 2 + 7 = 11 in all.
More board questions on this topic
- What is the relative atomic mass of an element whose one atom has…
- How many moles are there in 100 g of potassium dichromate?
- Which is the formula of aluminium carbonate?
- If enough vinegar is added to the reaction vessel, what is the…
Your account is open, so all 30,000+ MCQs from every chapter are yours. Start practising SSC Chemistry →
Want to keep going?
A free account carries you on to the next questions and opens 30,000+ MCQs from every chapter. Join before launch and Chirkut bundles are 60% off.
The ones you missed, worth one more look