Answer:
Nitrogen reacts with oxygen to form a number of nitrogen oxides. It exhibits different oxidation states in its oxides, ranging from +1 to +5. Oxides of nitrogen having nitrogen in the higher oxidation state are more acidic than that in lower oxidation state. Nitrogen oxides are critical components of photochemical smog. They produce the yellowish-brown colour of the smog. In poorly ventilated situations, indoor domestic appliances such as gas stoves and gas or wood heaters can be significant sources of nitrogen oxides.
Following are the harmful effects caused by the oxides of nitrogen
Nitrogen oxides causes irritation in mucous membrane.
Large concentrations of Nitrogen oxide causes lungs problems in humans
It causes injuries to vegetation by damaging leaves.
Nitrogen oxide oxidizes Hydrocarbons in the presence of sunlight, which causes eye irritation, asthama attacks, nasal and throat infections.
NO: sharp, sweet-smelling, colourless gas. Melting point: -163.6°C. Boiling point: -151.8°C. Relative Density: 1.04 (air = 1) NO2: reddish-brown gas with irritating odour
The number of covalent bonds is determined by the number of valence electrons of an element. The number of electrons tells the maximum number of bonds an element allows. In this case, an oxygen atom requires two bonds. So for Sio2, each oxygen atoms are bonded in double bonds to Si. Hence there are two covalent bonds.
Researchers have shown that when really small particles are close to each other like in a nebula, they are attracted to each other due to electromagnetism (from static electricity) since the masses are too small for gravity to really matter. However, the answer is probably gravity, electromagnetism only played a small role in the very beginning when nothing had enough mass. After that, gravity caused everything to condense and gravity did a better job once everything had enough mass for gravity to matter.
I hope this helps, let me know if anything is unclear in the comments.
B, C and E. In radioactive decay unstable atoms stabilize by releasing energy.
