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Q. 3. State the first limitation of Mendeleev’s periodic table. 1

Ans. Limitation of Mendeleev’s periodic table:

1. The position of isotopes could not be explained as isotopes are the atoms of the same element having similar chemical properties but different atomic masses.

Q. 4. Redraw the diagram given in your answer book and show the direction of the light ray after refrection from the lens.

Ans.

Q. 5. A wire of resistance 20  is bent to form a closed square. What is the resistance across a  diagonal of the square?

Ans. Total resistance of the wire = 20
AB = BC = CD = AD

Resistance across AC is given by R

Science 2009 Question Papers Class X
Delhi		Outside Delhi		Compartment Delhi		Outside Delhi		Foreign
	Set 1 (PDF)		Set 1 (PDF)		Set 1		Set 1		Set 1 (PDF)
					Set 2		Set 2
					Set 3		Set 3