<span>The rare earth elements include the lanthanide series, scandium and yttrium. They are a set of seventeen chemical elements in the periodic table. They really are not that rare but they occur together in nature and are hard to separate from one another.</span>
It says
The majority of elements on the periodic table are ______________ (metals, nonmetals, or metalloids).
The periodic table on the left separates elements into three groups: the metals (green in the table), nonmetals (orange), and metalloids (blue). Most elements are metals.
Apr 18, 2003
Answer:
option C= 12.40
Explanation:
Formula:
pH + pOH = 14
First of all we will calculate the pH.
pH = - log [H⁺]
pH = - log [0.025]
pH = - (-1.6)
pH = 1.6
Now we will put the values in formula,
pH + pOH = 14
pOH = 14-pH
pOH = 14 -1.6
pOH = 12.4
The pOH of solution is 12.4.
Answer: 68
Explanation:
Isotopes of an element have same number of protons but different number of neutrons. Which means isotopes of an element have same atomic number but different mass number.
Atomic number is equal to the number of protons or the number of electrons for a neutral atom and is specific to a particular element.
Mass number is the sum of number of protons and the number of neutrons.
Given : atomic number of element Q = 68 = number of protons
Mass number of isotope Q-136 = 136
But as isotopes have same atomic number, the number of protons will be same and hence there are 68 protons are in a neutral atom of this isotope.
