crossword
Crossword
Complete the crossword, then click on "Check" to check your answer. If you are stuck, you can click on "Hint" to get a free letter. Click on a number in the grid to see the clue or clues for that number.
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Check
Across:
3.
'Z' is the symbol of ...........
5.
An isotope of ............... is used as a fuel in nuclear reactors
Down:
1.
.....................have the same atomic number but different mass numbers
2.
there are .............. isotopes of hydrogen atom,
4.
protons and neutrons are also called ...................
OK