The answer is Hydrogen
This is what happens when acids react with metals
no the best source is blood.
Answer : The correct option is, (B) 
Solution :
According to the Graham's law, the rate of effusion of gas is inversely proportional to the square root of the molar mass of gas.

or,
..........(1)
where,
= rate of effusion of unknown gas = 
= rate of effusion of oxygen gas = 
= molar mass of unknown gas = ?
= molar mass of oxygen gas = 32 g/mole
Now put all the given values in the above formula 1, we get:


The unknown gas could be carbon dioxide
that has approximately 44 g/mole of molar mass.
Thus, the unknown gas could be carbon dioxide 
Answer:
Cupric ions
Explanation:
In the single displacement reaction shown, the cupric ions lost two electrons.
Cu²⁺ + 2e⁻ → Cu
The replacement of a metallic ion in solution by a metal atom higher in the activity series than than the metal in solution falls into this category of reactions.
Since Zn higher in the series, it displacements the cupric ions.
Of Uranium-235 remains after 2.8 x 10^9 years, what was the original mass of the sample of Uranium-235? The half-life of Uranium-235 is 7.0 x 10^8 years. Uranium-232 has a half life of 68.8 years.