Answer:
100
Explanation:
Step 1: Subtract 50 by 300 to find the total mass of the marbles
300 - 50 = 250
Not hard, right?
Step 2: Divide 250 by 2.5
250 ÷ 2.5 = 100
And... 100 is your answer :)
Hope this helps :)
-jp524
Answer:
d. Radon-222
Explanation:
²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He
Alpha particle is a helium nucleus with mass number 4 and atomic number 2. According to the law of conversation of mass, the sum of the mass number and atomic number must be equal on both side of the reaction.
Since the mass number of Ra is 226 and that of He is 4. The mass number of the unknown element must be 226 - 4 = 222.
Since the atomic number of Ra is 88 and that of He is 2. The atomic number of the unknown element must be 88 - 2 = 86.
Now looking in the periodic table Radon is the only element with atomic number 86.
The general formula for a decomposition reaction is shown as option C. AB -> A + B. This type of reaction is simply when a complex compound and or substance is broken down to form its substituent atoms of their respective elements. It is energy releasing as compounds are broken down and is the inverse of a synthesis type of chemical reaction.
