Lead.
Lead paint was a big problem and now lead has been removed from paint because it was found to be dangerous to the health of living organisms.
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Given, half life of a certain radioactive element = 800 years.
Amount of substance remaining at time t = 12.5%
Lets consider the initial amount of the radioactive substance = 100%
Using the half life equation:
A = A₀(1/2)^t/t₁/₂
where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.
Plugging the given data into the half life equation we have,
12.5 = 100 . (1/2)^t/800
12.5/100 = (1/2)^t/800
0.125 = (0.5)^t/800
(0.5)^3 = (0.5)^t/800
3 = t/800
t = 2400 years
Thus the object is 2400 years old.
<span>8.21 L of C3H8(g)
Lets take c as the molar volume at that temperature.
c L <><> 5c L
C3H8 (g) + 5O2 (g) --> 3CO2 + 4H2O + Q
8.21 L <><> x L
x = (8.21 * 5c)/c = 8.21 * 5 = 41.05 L O2 consumed for a 100% yield.</span>
Answer:
Abrasion
Explanation:
Here's an example, strong winds on a beach where some rocks are cause the sand to rub against the rocks, causing heat and eventually crack and destroy the rock. The ice of glaciers can also break down rocks when rocks are frozen inside it, and that's cooling.
1)The limiting reactant will be aluminum acetate
2) The mass of aluminum hydroxide formed will be 9.75 grams.
<h3>Stoichiometric problem</h3>
The equation of the reaction is as below:
The mole ratio of the 2 reactants is 1:3.
Mole of 100 mL. 1.25 mol/L 
= 0.1 x 1.25 = 0.125 mol
Mole of 300 mL, 2.30 mol/L NaOH = 0.3 x 2.3 = 0.69 mol
Thus, aluminum acetate is limited.
Mole ratio of and 
= 1:1
Equivalent mole of = 0.125 mol
Mass of 0.125 mole = 0.125 x 78 = 9.75 grams.
More on stoichiometric calculations can be found here: brainly.com/question/27287858
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