Answer:
CH₃NH₃⁺ is a weak acid.
HPO₄²⁻ has a negligible acidity.
CH₄ has a negligible acidity.
HNO₂ is a weak acid.
Explanation:
There are 7 strong acids: HCl, HBr, HI, HNO₃, H₂SO₄, HClO₃, HClO₄. The rest of the acids are weak.
CH₃NH₃⁺ is a weak acid, according to the following equation:
CH₃NH₃⁺ ⇄ CH₃NH₂ + H⁺
HPO₄²⁻ can act as an acid or as a base:
<u>Acid reaction:</u> HPO₄²⁻ ⇄ PO₄³⁻ + H⁺
<u>Basic reaction:</u> HPO₄² + H₂O ⇄ H₂PO₄⁻ + OH⁻
Given Kb > Ka, HPO₄²⁻ has a negligible acidity.
CH₄ cannot release nor accept H⁺ so it has a negligible acidity.
HNO₂ is a weak acid, according to the following reaction:
HNO₂ ⇄ H⁺ + NO₂⁻
<span>The answer is true that Group 1A elements (except for hydrogen) are the
alkali metals. Groups 2A are alkaline earth metals. Group 3B-12B are transition
metals. Group 3A to 4A except Boron, Carbon, Nitrogen, oxygen, silicon,
phosphorus, sulfur, germanium, astatine, selenium, antimony, tellurium, polonium
are basic metal. Carbon, nitrogen, oxygen, phosphorus, sulfur and selenium are
nonmetals. Boron, silicon, germanium, astatine, antimony, tellurium and polonium
are metalloids. Groups 7A are halogens. Groups 8A are noble gases. The lower
part of the periodic table are lanthanides and actinides.</span>
The Answer should be A. A consensus is defined as a general agreement so it is something most scientists would believe.
Low melting and boiling points, very soft, have low densities, react quickly with water, and their hydro-oxides and oxides dissolve in water to form alkaline solutions.
