Answer:
D
Explanation:
Because the number of protons is the same as the atomic number, we know what the number of protons has to be 26. The mass number, 55, is the same as the number of protons plus neutrons. Lastly, because there is no charge on this atom, the number of electrons would have to be the same as the number of protons, which is 26.
Answer:A
Explanation:
The melting points of solids depend in the relative sizes of ions in the ionic lattice. The smaller the relative sizes of the ions, the higher the lattice energy and the stronger the lattice hence higher melting point. Comparing relative ionic sizes, fluoride ion is lesser in size than chloride ion hence NaF has a higher melting point than NaCl.
Answer:
1.635 M
Explanation:
Given:
10 mL of 20 volumes Hydrogen Peroxide
Here,
20 volumes of Hydrogen Peroxide means that on decomposition of 1 mL of H₂O₂ 20 mL of O₂ is obtained
also,
means 1 dm³ of H₂O₂ solution produces 20 dm³ oxygen
Now,
at 298K and 1 atm
20 dm³ oxygen = 
moles
or
= 0.817 moles
also,
2H₂O₂ → 2H₂O + O₂
thus,
1 dm³ of solution must contain 2 × moles of O₂ as moles of H₂O₂
thus,
Number of moles of H₂O₂ = 2 × 0.817
or
Number of moles of H₂O₂ = 1.635 moles
Hence,
For 20 volume hydrogen peroxide is 1.635 M
