1 half-life - 4.5 days
x half-lives - 27 days
x=(1*27)/4.5=6
6 <span>half-lives have elapsed after 27 days.</span>
ANSWER IS (A)
EXPLANATION:
Bronsted-Lowry concept states that a substance is an acid if it can act as a H+ donor.
HCl in aqueous solution means that HCl is present in water, HCl + H2O --> H3O+ + Cl-. This reaction will take place, the H+ from HCl will be donated to H2O. So, HCl is a bronsted-lowry acid by definition.
However, Methanol (CH3OH) its written that it is liquid, i.e. pure methanol, CH3OH(l). It is both acidic as well as basic. when it is mixed with water then it behaves as an acid.
The last one ammonia in gas phase is also neutral because its not in water. if mixed in water it behaves as a base.
The volume of oxygen required to burn 12.00 L ethane is calculated as follows
find the moles of C2H6 used
At STP 1 mole is always = 22.4 L, what about 12.00 L
= ( 12.00L x 1 moles) 22.4 L = 0.536 moles
write the reacting equation
2C2H6+ 7O2 = 4CO2 + 6H2O
by use of mole ratio between C2H6 :O2 which is 2:7 the moles of O2
= 0.536 x7/2= 1.876 moles
again at STP 1mole = 22.4 L what about 1.876 moles
= 22.4 L x 1.876 moles/ 1 mole = 42.02 L
Answer:
Resistance
Explanation:
Resistance is the measure of the opposition of current in a circuit.
Answer:
The elements become less reactive.
Explanation:
As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction and reactivity increases because of greater electron affinity.
As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased. The electron affinity decreases because of shielding effect and thus atom become less reactive.
