The halogens are five non-metallic elements found in group 17 of the periodic table. The term "halogen" means "salt-former" and compounds containing halogens are called "salts". All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1.
The following are the statements, which indicates that the fossil record suggests about evolution on Earth:
1. Humans have only recently existed on Earth.
2. The organisms originally lived only in Earth's water.
3. The plants did not have flowers when dinosaurs existed.
The fossil remains have been discovered in the rocks of all the ages. The simplest organisms fossils are witnessed in the oldest rocks, and the fossils of more composite species are found in the newest rocks. This supports the theory of evolution suggested by Darwin, according to which the simple life forms slowly gets evolved into more composite ones.
According to Bronsted-Lowry reaction- an acid is any substance that donates a proton (H+ ion) to another substance hence these two substance are acid aspirin (acetylsalicyclic acid) and hydrochloric acid (HCl). And there are two pairs - an acid with a corresponding conjugate base and a base with a corresponding conjugate acid. These pairs are called conjugate acid-base pairs.
The correct answer is + 32.5 J because heat is absorbed here by copper not evolved also after calculation we will find the H value is positive, lets calculate it:
H = m C Δt where:
m = 10 g
C = 0.13 J/g.°C
Δ t = final temperature - initial temperature = 50 - 25 = + 25 °C
so H = 10 x 0.13 x (+25) = + 32.5 J
