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CBSE X
Set -2
SCIENCE PAPER 2009

Time allowed: 150 minutes; Maximum Marks: 60

General Instructions:
1)  All questions are compulsory.
2) The question paper consists of 27 questions divided into 4 sections A, B, C and D. Section A comprises questions of 01 mark each, Section B comprises questions of 02 marks each, Section C comprises questions of 03 marks each and Section D comprises questions of 05 marks each.
3)  All questions in Section A are to be answered in one word, one sentence or as per the exact requirement of the question.
4) There is no overall choice. However, internal choice has been provided wherever necessary.You have to attempt only one of the alternatives in all such questions.
5)  In question on construction, drawing should be near and exactly as per the given measurements.
6) Use of calculators is not permitted.

SECTION A

Question 1

1. Balance the following chemical equation:

Pb(NO3)2(s) →PbO(s) + NO2(g) + O2 (g)

Question 2

2. Fresh milk has a pH of 6. When it changes into curd (yogurt) will its pH value increase or decrease? Why?