Answer: An Element
Explanation:
An element is a substance that cannot be split into smaller substance. It is made up of one kind of atom and can exist either as molecules (e.g nitogen) or an atom (e.g argon).
Latent heat of melting is the energy that a solid absorbs to change its phase as its liquid. During this process, since all energy is used to change the phase, the temperature is constant.
Here the latent energy of melting for 1 g of ice is 80 calories and that 1 g of ice only absorbed 60 calories. hence the phase is not changed because it requires more 20 calories to melt.
Hence 1 g of ice remains as its solid phase (ice).
Answer
thus, 4 moles of oxygen gas (O2) would have a mass of 128 g.
Answer:
electrons move around the nucleus in fixed orbits of equal amounts of energy
Explanation:
Quantum Theory
Answer:
The decreasing order of bond length in the carbon - carbon bonds will be:

Explanation:
Bond length is defined as average distance between two nuclei of bonded atoms in a molecule.Bond length is inversely proportional to the number of bonds present between two atoms.
...[1]
Bond energy is defied as amount of energy required to break apart the bond of 1 mole of molecule into their individual atom. Bond energy is directly proportional to the number of bonds present between two atoms.
..[2]
From [1] and [2]:

hybridized
hybridized
hybridized
Extent of overlapping of orbitals in these hybridization;

Higher the overlapping of orbital more closer will be both atoms to each other and shorter will be the bond lenght.
So, the decreasing order of bond length in the carbon - carbon bonds will be:
