The amount of matter in an object is consisted to be MASS .
• Bubbles of a colourless, odourless gas are evolved
• The solution turns red litmus blue
Ca + 2H_2O→ Ca(OH)_2 + H_2
According to the Aufbau principle, , electrons orbiting one or more atoms fill the lowest available energy levels before filling higher levels (e.g., 1s before 2s).
You have to be very careful with this question. A change in mass can also occur in chemical changes especially if you have too much of something. For example
CH4 + 1.5 02 ===> CO2 + H2O
If you have too much of either CH4 or O2, there will be some CH4 or O2 left over. There has been a change in mass that you have too much of.
However that is not the point of the question. It is just something you need to be aware of.
Suppose you have a piece of aluminum and you take a course grinder after it. You will change the texture of the side you took the grinder to. If the aluminum has been anodized (a color has been put on it's surface), you may grind the color off or if it is just plain aluminum, you may roughen the surface, but you won't change what the aluminum will do chemically.
You may need only a small portion of the aluminum and you grind off just what you need. That will change the mass of both what you took off and the piece that you want, but the aluminum will still do whatever chemical property you need to use.
So you can change both texture and mass without changing the chemical properties of the substance whose mass or texture you are changing.
Answer: 20 gallons of 16% and 8 gallons of 23% solution is usedfor 28 gallons of the 18 % solution.
Explanation:
According to the dilution law,
where,
= concentration of ist disinfectant solution = 16 %
= volume of pure acid solution = x gallons
= concentration of another disinfectant solution= 23%
= volume of another acid solution= (28-x) gallons
= concentration of resulting disinfectant solution = 18 %
= volume of resulting acid solution = 28 gallons
(28-x) = (28-20) = 8 gallons
Thus 20 gallons of 16% and 8 gallons of 23% solution is usedfor 28 gallons of the 18 % solution.
