Combustible: Charcoal, straw, cardboard, paper, candle, wood.
Non-combustible: Chalk, stone, iron rod, copper coin, glass.
Objects that produce heat are coal, liquid fuels, gasoline, oil, and gaseous fuels
HCl is because h+ is produced
Answer:
C. I, III , IV
Explanation:
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required.
As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.
As the size of atom increases the ionization energy from top to bottom also decreases because it becomes easier to remove the electron because of less nuclear attraction and as more electrons are added the outer electrons becomes more shielded and away from nucleus.
Answer:
Is a substance that can maintain certain range of pH
Explanation:
A buffer is mixture of two salts that are complementary, one salt is acid and another is basic, but since then share some part of their structure, if you add to this mixture another acid, the basic salt can absorb it and still maintaining the same pH. If you pour a base, the acid salt will absorb it and again the final pH will remain the same. So the buffers are used to maintain the same pH does not matter if you add small quantities of an acid or base.
