Matter in Our Surroundings — Science STD 9 — Question

The atomic number of an element E is 16. The number of electrons in ion E^2- will be:

1. 16
2. 18
3. 15
4. 14

Which of these would support the idea that mass is conserved in a reaction that produces gas as a product:

Which of the following does not have a fixed melting point/ boiling point?

1. Gold.
2. Ethanol.
3. Air.
4. Oxygen.

The interparticle attractive force ......... with increasing distance between particles:

You are given the following substances with their boiling and melting points.

Substance	Boiling Point (ºC)	Melting Point (ºC)
A	-183	-219
B	445	119
C	78	-15

Point out the physical states of A, B and C at room temperature (30°C).

The nucleus of the hydrogen atom is called as:

Which one of the following sets of phenomena would increase on raising the temperature?

A liquid is found to scatter a beam of light but leaves no residue when passed through the filter paper. The liquid can be described as:

Match the Column I with Column II.

S.No	Column I		Column II
a	9.033 × 1024 atoms	i	46g of He
b	2 moles of Na	ii	15 moles
c	11.2 L of O2, at STP	iii	3.011 × 1023 molecules
d	22g of CO2	iv	16g