Which element is a metalloid?
a. argon (ar)
b. silicon (si)
c. potassium (k)
d. magnesium (mg) user:
looking at the periodic table, which element is a metal?
a. argon (ar)
b. silicon (si)
c. hydrogen (h)
d. strontium (sr)

Which element is a metalloid? B. Silicon (Si)

Looking at the periodic table, which element is a metal? D. Strontium (Sr)
Argon (Ar) is a noble gas, silicon (Si) is a metalloid, hydrogen (H) is a non-metal, and strontium is a alkaline earth metal.

I have used the periodic table from http://chemreference.com/elements/1/properties?display=periodic&trend=number to help me when I'm unsure.

 ¹₀n

Explanation:

The given expression is:

          ²⁷₁₃Al      +     ₐᵇT   →   ²⁴₁₁Na    +    ⁴₂He

This expression is typical of nuclear reactions. To balance this expression we must conserved the mass number and the atomic number.

The mass number is the superscripts and the atomic number is the subscript;

 Now;

 conserving mass number:

             27 + b  = 24 + 4

             27 + b  = 28  

                   b  = 28 - 27  = 1

conserving the atomic number;

            13 + a  = 11 + 2

             13 + a  = 13

                    a  = 0

So;

The particle T is a neutron    ¹₀n