grade 6 8 science

Question: Why are the two non-metals, carbon and hydrogen are important chemical reference points with regard to the method of metal extraction and reactivity towards acids. Answer: The six metals K, Na, Li, Ca, Mg, and Al, which lie above carbon in the activity series, cannot ..

Question: In the figure, 1. 6 W , 3 W and 9 W are in series 2. 9 W and 6 W are in parallel and the combination is in series with 3 W 3. 3 W , 6 W and W are in parallel 4. 3 W , 6 W are in parallel and 9 W is i..

Question: What do you understand by atomicity of an element? Give an example of a polyatomic molecule. Answer: The number of atoms that constitute one molecule of an element is called its atomicity. Sulphur is a polyatomic molecule: S 8 - 8 is the atomicit..

Cell division is a method by which new cells are originated from pre-existing cells. The formation of daughter amoebae in amoeba, the development of sex cells and the growth of a young animal or plant into an adult, all involve cell multiplication. In order to multiply in number, cells undergo cell..

A - 2, 8, 2 - It is a metal as it has 2 valence electronsB - 2, 8, 6 - It is a non-metal as it has 6 valence electronsC - 2, 6 - It is a non-metal as it has 6 valence electr..

Indigenous dairy breeds produce 6-8 litres of milk a day where as foreign exotic breeds produce 60 litres of milk a da..

Isotones Atomic number(Z) MassNumber(A) Electrons(e) Proton(p) Neutron(n) 14 C 6 6 14 6 6 8(14-6) 15 N 7 7 15 7 7 8(15-7) 16 O 8 8..

Group I A elements Electronic configuration No.of elememnts Hydrogen 1 1 Lithium 2,1 2 Sodium 2,8,1 3 Potassium 2,8,8,1 4 Rubidium 2,8,18,8,1 5 Caesium 2,8,18,18,8,1 6 Fr..

) 12 2 8 2 Aluminium (Al) 13 2 8 3 Potassium (K) 19 2 8 8 1 Calcium (Ca) 20 2 8 8 2 Non-metals Nitrogen (N) 7 2 5 Oxygen (O) 8 2 6..

? One has not anticipated some of the impacts of industrial and technological advancement. When the industrial revolution started some 250 years ago, the world population was at 600 million - that seems like a lot of people but now the world population is now almost ten times at 6 billion..