hold the syringe downward,shake vigorously for sometime,and expel the bubbles through the needle using the syringe plunger. hold the syringe upright, provide a firm tap or flick to the barrel
Answer:
The wood
Explanation:
The block of wood shall float in the water while the iron key would sink due to the weight.
Answer : The value of diffusion coefficient is, 
Explanation :
Formula used :

where,
D = diffusion coefficient = ?
= 
= 
R = gas constant = 8.314 J/mol.K
T = temperature = 
Now put all the given values in the above formula, we get:


Thus, the value of diffusion coefficient is, 
Sorry but NaCl is a ionic compound not an element though it's made up of two elements sodium and chlorine
If you double the concentration of A, the rate is doubled. If you doubled the concentration of B, since the rate law has B^2, the rate is multiplied by 4. If you double both A & B's concentrations, then the rate would be multiplied by 2*4 = 8, which is the last option.