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
Answer:
11·699
Explanation:
Given the concentration of hydroxide ion in the solution is 5 × 
M
Assuming the temperature at which it is asked to find the pH of the solution be 298 K
<h3>At 298 K the dissociation constant of water is
</h3><h3>∴ pH + pOH = 14 at 298 K</h3><h3>pOH of the solution = -log( concentration of hydroxide ion )</h3>
∴ pOH of the given solution = - log(5 × = -0·699 + 3 = 2·301
pH of the given solution = 14 - 2·301 = 11·699
∴ pH of the solution = 11·699
Answer is: lithium is the least reactive and potassium is the most reactive of the three alkali elements.
<span>The </span>reactivity<span> of the alkali metals increases down the group because one valence electron (I group of Periodic system of elements) is farther away from nucleus and attraction force between electron and proton is weaker.</span>
<span>The ratio of oxygen-16 and oxygen-18 isotopes in plankton fossils in deep-sea sediments can be used to determine past temperatures.</span>
