(Download) INJSO Olympiad Question Papers 2018

Question paper
Exam Name : INJSO Olympiad Question Papers 2018

Section B

Question 31 (A) PD of 1 V, gains 2 eV therefore charge of ion is -2 C

• The number of electrons in the ion = X
• Then the number of neutrons will be X + 25 X/ 100 = 1.25X
• The number of electrons in the neutral atom = X-2
• The number of protons in the neutral atom = X -2
• Mass number = No. of Protons + No. of neutrons
• 79 = X-2 + 1.25X
• 2.25 X = 81
• X = 81 / 2.25 = 36

Number of protons = 36 – 2 = 34 Hence the element is Se Symbol of Ion is Se-2

(B) A = Ca B= CaOCl₂ Y= Ca(OH)2 Z= CaSO₄

•   Reactions: 2Ca + O₂  2CaO
•   CaO + H₂O  Ca(OH)₂
•   Ca (OH)₂ + H₂SO₄  CaSO₄ + 2H₂O
•   Ca (OH)₂ + Cl₂  CaOCl₂ + H₂O
•   OR 2Ca(OH)₂ + 2Cl₂  Ca(ClO)₂ + CaCl₂ + 2H₂O

Click Here to Download Full Paper

Olympiad Exam BOOKS

Courtesy: Science Olympiad Foundation

<< Go Back to Main Page