Answer:
Both K+ and NO3- concentrations are halved
Explanation:
Since the reaction is
K₂Cr₂O₇ + Pb(NO₃)₂ 2K(NO₃) + <u>PbCr</u>₂<u>O</u>₇
knowing that K+ and NO3- are spectator ions, their concentration do not change due to reaction but it will change due to the mixing of volumes of the reactants since we are mixing volumes of different concentrations.
for K+ initially we have:
c K+ initial = 0.25 M
c K+ final = n/ V = C i * Vin / Vfinal = 0.25 M * 100 ml / 200 ml = 0.125 M
the 200 ml comes from mixing the 100 ml of Pb(NO₃)₂ and 100 ml of K₂Cr₂O₇ ( assuming that the volume of the precipitate is insignificant relative to the solution , it does not occlude a significant portion of the saturated solution and assuming that any volume contraction/expansion due to non ideal behaviour of the solution is negligible)
the same happens with NO3- ,therefore its concentration is also halved
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Answer:
The correct answer is - C) 3 hours.
Explanation:
Given:
The half-life = 1 hour
Solution:
The half-life of an element is the time required to decay half of its initial amount.
To complete 87.5%, there total numbers of half-live would be -
1st halflife = 50% of the initial amount
2nd half-life = 50 + 50% of (50) = 50 +25 = 75% of initial amount
3rd half-life = 50 + 50 % of (50) + 50% of (25) = 87.5% of initial amount
so, to complete the 87.5 % of decay it required 3 half lives, and each half-life take one hour thus, total time taken = 3 hours
<span>Isotopes are atoms of a particular element that contain a different number of neutrons.
An atom or element have same number of protons and electrons, but when there is a change in number of neutrons, this is called isotope of that element. There are many elements that have their isotopes like carbon have three isotopes Carbon 12, 13 and 14.</span>