The answer to the question is radium (Ra)
Answer:
The number of electrons in the outermost shell of an atom determines its reactivity. Noble gases have low reactivity because they have full electron shells. Halogens are highly reactive because they readily gain an electron to fill their outermost shell.
Explanation:
I hope this helped!
Answer:
mass/13of molecules .........
Answer:
50 g of K₂CO₃ are needed
Explanation:
How many grams of K₂CO₃ are needed to make 500 g of a 10% m/m solution?
We analyse data:
500 g is the mass of the solution we want
10% m/m is a sort of concentration, in this case means that 10 g of solute (K₂CO₃) are contained in 100 g of solution
Therefore we can solve this, by a rule of three:
In 100 g of solution we have 10 g of K₂CO₃
In 500 g of solution we may have, (500 . 10) / 100 = 50 g of K₂CO₃
Answer:
The pressure inside the flask is 0,09 atm
Explanation:
We calculate the number of moles of O2, we convert the Temperature into unit KELVIN and use the formula of the ideal gases to calculate the pressure:
Weight 1 mol of 02= 15,999g x2= 32g
32g---1mol 02
0,60g---x=(0,60gx1mol O2)/32g= 0,019mol O2
T(K)=273+22=295K
PV=nRT
Px5.0l= 0,019mol x 0,082 lxatm/Kxmolx295 K
P=(0,019mol x 0,082 lxatm/Kxmolx295 K)/5.0l
P=0,09atm
