Answer:
31.64...
Explanation:
The formula is volume is equal to mass over density.
So 25/0.79=31.64...
Pure substance - Ice cubes
Mixture - Homogenous sea water , lemonade
Pure substance are the substance which have constant chemical composition and characteristic.
Mixture is material made up of two or more chemical substance which are not chemical bonded. These materials in mixture are not in definite proportion.
As water ice cubes has only water in it thus it is pure substance.
Homogeneous sea water contains various salts and impurities in it thus it is mixture.
Lemonade contains lemon juice and water in it . Thus, it is mixture.
To know more about pure substance and mixture
brainly.com/question/6459860
#SPJ4
<span>Answer: 8.15s
</span><span />
<span>Explanation:
</span><span />
<span>1) A first order reaction is that whose rate is proportional to the concenration of the reactant:
</span><span />
<span>r = k [N]
</span><span />
<span>r = - d[N]/dt =
</span><span />
<span>=> -d[N]/dt = k [N]
</span><span />
<span>2) When you integrate you get:
</span><span />
<span>N - No = - kt
</span>
<span></span><span /><span>
3) Half life => N = No / 2, t = t'
</span><span />
<span>=> No - No/ 2 = kt' => No /2 = kt' => t' = (No/2) / k
</span><span />
<span>3) Plug in the data given: No = 0.884M, and k = 5.42x10⁻²M/s
</span>
<span /><span /><span>
t' = (0.884M/2) / (5.42x10⁻²M/s) = 8.15s</span>
