Choose the elements whose atoms you expect to have greater shielding effects? (i) Be or Mg
(iii) F or Cl
(ii) C or Si
(iv) B or Al
with full explanation

Some animals that try to adapt to climate changes eventually die due to starvation, as climate change alters the web.

An alloy contains 66 g of pure zinc. what is the percentage of zinc in the alloy? express your answer to two significant figures and include the appropriate units.

Hydrogenation reactions, in which h2 and an "unsaturated" organic compound combine, are used in the food, fuel, and polymer industries. in the simplest case, ethene (c2h4) and h2 form ethane (c2h6). if 140 kj is given off per mole of c2h4 reacting, how much heat (in mj) is released when 12 kg of c2h6 forms?