Elements and Compounds

Assertion: Elements and compound are the examples of pure substances. Reason : The properties of a compound are different from those of its constituent elements.

Statement-1 : Entropy of all elements is zero at zero Kelvin. Statement-2 : Standard entropy of all elements is greater than zero. Statement-3 : Entropy of all elements and compounds decreases with decrease of temperature and becomes zero at absolute zero temperature.

Select elements and compounds from the following list: Iron, plaster of paris chalk, common satl copper alumminum , calcium oxide , cane sugar , cargon silica , sodium sulphate , uranium , potassium carbonate, silver , carbon dioxide.

Define: (a) Elements (b) Compounds.

State two differences between an element and a compound.

State five different characteristics of compounds. Give three differences between elements & compounds with relevant examples.

Select the correct answer from A, B, C, D & E for each statement given below: A: Gunpowder B: Iodine C: Boron D: Helium E: Bromine 1. A diatomic molecule. 2. A metalloid 3. A non-metal which is lustrous. 4. A mixture consisting of elements & a compound. 5. A noble gas.

Classify the following substances as either being an element or a compound?

The smallest particle of an element or a compound which has independent existence

Define the terms elements, compounds & mixtures with a view to show their basic difference.