Answer: 3.72 M
Explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = age of sample = 15.0 minutes
a = let initial amount of the reactant = 10.0 M
a - x = amount left after decay process = ?




The concentration of
in a solution after 15.0 minutes have passed is 3.72 M
Answer:
Rock
Explanation:
Let's calculate the density of each object:
Rock:
Pencil:

Therefore the rock is denser.
Fe3N2, also known as Iron (II) nitride, is an ionic compound.
Ionic compounds are compounds that consists of metals and non-metals bonded with ionic bonds. The metal ion gives up electron(s) to the non-metals.
Since iron is a metal and nitrogen is an non-metal, the bond they would form would be an ionic bond. Iron gives up 2 electrons to form iron(II) ion, while nitrogen gains 3 electrons to form nitride ion. Since one iron cannot let a nitrogen gain 3 electrons, so in the compound, there would be 3 iron (ii) ions that has given up 6 electrons in total while 2 nitride ions have gained 6 electrons in total.
I think its A.
if one force cannot overcome the other, the object remains stationary.
Answer: COMBINED FORCES
When forces act in the same direction, they combine to make a bigger force. When they act in opposite directions, they can cancel one another out. If the forces acting on an object balance, the object does not move, but may change shape.
Explanation: