Answer:
Rock
Explanation:
Let's calculate the density of each object:
Rock:
Pencil:

Therefore the rock is denser.
Answer is: formula of the complex is [Cr(NH₃)₂(SCN)₄<span>]</span>⁻<span>.
This complex has negative charge (-1) because chromium (central atom or metal) has oxidation number +3, first ligand ammonia has neutral charge and second ligand thiocyanate has negative oxidation number -1:
+3 + 2</span>·0 + 4·(-1) = -1.
According to avogadro constant, the number of units in one mole of any substance contain 6.022 x10 ^23 atoms
therefore the number of o atoms in one mole of CuSO4 = 6.022 x 10 ^ 23
Sodium (Na) has a +1 charge and Iodine ( I ) has a -1 charge. To create a molecule of sodium iodide the charges will need to balance.
Because the charges on anion and cation are the same; the molecular formula will be NaI