Answer: The mole ratio of Zn to ZnO is 3: 3.
Explanation:
According to law of conservation of mass, mass can be neither be created nor be destroyed. The mass on reactant side must be equal to the mass on product side. Thus the atoms of each element on both side of the reaction must be same.
The balanced chemical reaction is:

Here 3 moles of Zn combine with 2 moles of
to give 1 mole of
and 3 moles of
. Thus the mole ratio of Zn to ZnO is 3: 3.
Answer:
See image attached for structure of CH3Br
Explanation:
A lewis structure structure is a representation of a covalent compound in which dots are used to show valence electrons, lone pairs and bonding electrons. The system was introduced by sir G.N Lewis in 1916 in his article titled 'Atom and Molecule'. They are also called dot electron diagrams of molecules. CH3Br molecule contains a total of fourteen electrons. Valence electrons are shown by dots around the atom of each element as clearly seen in the image attached.
Can I see a picture please so i can answer your question
Density = Mass / Volume
V = 1.00 * 4.00 * 2.50 = 10 cm³
22.57 g/cm³ = Mass / 10 cm³
M = 22.57 g/cm³ * 10 cm³
M = 225.7 g
Answer: The mass of the block of osmium is 225.7 g.