<span>Balancing the choices, we have as follows:
A. 3AgBr + GaPO4 → Ag3PO4 +GaBr3
B. 3H2SO4 + 2B(OH)3 → B2(SO4)3 + 6H2O
C. Fe + 2AgNO3 → Fe(NO3)2 + 2Ag
D. C2H4O2 +2O2 → 2CO2 + 2H2O
Therefore, the correct answers are option A and B. Hope this answers the question. Have a nice day.</span>
Answer:
C, increases/decreases
Explanation:
As you move down a group on the periodic table, the electronegativity of an element decreases because the increased number of energy levels puts the outer electrons very far away from the pull of the nucleus.
The addition of hydrofluoric acid and Naf( answer c) to water produces a buffer solution.
Naf is used because buffer consist of a weak acid and the salt of that base.Buffer also consist a weak base and salt of that base .Hydrofluoric acid is a weak acid thus the salt would be added is Naf to produce buffer solution.
Iodine and Calcium is the correct answer
Explanation:
given
mass =85*1000=85000kg
volume=850/100*100*100m3
now,
density=mass / volume
=85000kg/850000000m3
=1/10000kg/m3
=0.0001kg/m3
the density of the rock is 0.0001kg/m3.