Matter in Our Surroundings — Science STD 9 — Question

What is latent heat of vaporization:

Which of the following statements is incorrect:

The number of atoms in one mole of a substance is equal to ................?

Which of the following are homogeneous mixtures:

Four students A, B, C and D verified the law of conservation of mass by performing chemical reaction between barium chloride and sodium sulphate. All of them took 107.2g barium chloride solution and 116.1g of sodium sulphate solution and mixed them in the beaker of mass 150g. They reported their results as follows:

Students	Colour of reaction mixture after mixing	Mass of reation mixture in the beaker including mass of beaker
A	White Precipitate	383.3g
B	BrownPrecipitate	393.3g
C	WhitePrecipitate	373.3g
D	Brown Precipitate	363.3g

The correct observation is that of student.

In a chemical reaction 10.6g of sodium carbonate reacted with 12g of ethanoic acid. The products were 4.4g carbon dioxide, 1.8g of water and sodium ethanoate. The mass of sodium ethanoate formed is

Which of the following factors are responsible for the change in state of solid carbon dioxide when kept exposed to air?

1. Increase in pressure
2. Increase in temperature
3. Decrease in pressure
4. Decrease in temperature

1. (i) and (ii)
2. (i) and (iii)
3. (ii) and (iii)
4. (ii) and (iv)

In Rutherford's α-ray scattering experiment most of the alpha particles:

Which of the following is not a postulate of Dalton's atomic theory