Select good and bad conductors of heat from the following: copper, mercury, wood, iron, air, saw-dust, cardboard, silver, plastic, wool.

Select conductors of electricity from the following : Copper wire, silk thread, pure water, acidulated water,human body, glass, mercury.

Select conductors and insulators from the following: Glass, silver, copper, wood, paper, pure water, impure water, aluminium, iron, leather, plastic, steel, human body and ebonite.

Wood and plastic are good conductors of heat, so they are used to make handles of cookware.

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.

Select natural and man made matter from the following list: Wood,plastic,silk,medicines,detergents,coal,water,ceramic,cotton,glass,nylon,fruits.

From the list given below, choose and write the correct examples : Ammonium hydroxide, wood, plastic, silver, copper, glucose, acetic acid, urea, hydrochloric acid, sodium chloride solution

Certain metals exbibit variable valencies which include valencies 1^(+),2^(+),3^(+) & 4^(+) . State the variable valency of the following metals -a] Copper b] Silver c] Mercury d] Iron e] Tin f] Lead-[Write each symbol with the variable valency]

Explain the following : (a) Why is tungsten used almost exclusively for filament of incandescent lamp ? (b) Why are the conductors of electric heating devices, such as toaster and electric irons, made of an alloy rather than a pure metal ? ( c) Why is the series arrangement not used for domestic circuits ? (d) How does the resistance of a wire vary with its cross-sectional area ? (e ) Why are copper and aluminium wires usually employed for electricity transmission.

In 1894 , Lord Rayleigh reported that the mass of chemically prepared nitrogen was different from that of nitrogen extracted from the atmosphere, as shown in Tables 1 and 2 . Latter, this difference was attributed to the presence of argon in atmospheric nitrogen. The masses of gases were mearsured by using a glass vessel with a known volume under atmospheric pressure (1.013xx10^(5)Pa) . |{:("From nitric oxide",,2.3001 g),("From nitrous oxide",,2.2990 g),("From amonium nitrite purified at a red heat",,2.2987 g),("From urea",,2.2985 g),("From ammonium nitrite purified in the cold",,2.2987 g),("Mean",,2.2990 g):}| |{:(O_(2) "was removed by hot copper" (1892),,2.3103 g),(O_(2) "was removed by hot iron" (1893),,2.3100 g),(O_(2) "was removed by ferrous hydrate (1894),2.3102 g,),(Mean,,2.3102 g):}| Ramsay and cleve discovered helium in cleveite (a mineral consiting of uranium oxide and oxides of lead, thorium, and rare earths, an impure variety of uraninite) independently and virtually simultaneously in 1895 . The gas extracted from the rock showed a unique spectroscopic line at around 588 nm (indicated by D3 in Figure 1 ), which was fist observed in the spectrum of solar prominence during a total eclipse in 1868 , near the well-known D_(1) and D_(2) lines of sodium. ul("Identify") the transition relevant to the D_(3) line of helium among the transitions [A] to [E] indicated in Figure 2. Mark one of the following: [A] [B] [C] [D] [E]

Look at the picture of the thermos flask and answer the following question Would you expect the cork to be a good or a bad conductor of heat?