Question

who arranged the elements according to atomic mass and used the arrangement to predict properties of missing elements?
o h.g.j moseley
o antoine lavoisier
o john dalton
o dmitri mendeleev

of the elements pt, v, li and kr, which is a non - metal?
o pt
o v
o li
o kr

in which of the following sets is the symbol of the element, the number of protons, and the number of electrons given correctly?
o in, 49 protons, 49 electrons
o zn, 30 protons, 60 electrons

Explanation:

1. Dmitri Mendeleev arranged elements by atomic mass and predicted properties of missing elements.
2. Kr (Krypton) is a non - metal among the given elements. Pt (Platinum) and V (Vanadium) are metals, Li (Lithium) is a metal too.
3. In a neutral atom, the number of protons equals the number of electrons. For In (Indium), atomic number is 49, so it has 49 protons and 49 electrons. For Zn (Zinc), atomic number is 30, so it should have 30 electrons not 60.

Answer:

1. D. Dmitri Mendeleev
2. D. Kr
3. A. In, 49 protons, 49 electrons