It's a Gas!
Across
2. This gas can be used
to fill party balloons
4. This gas is
used to make yellow-green 'neon' signs.
6. This gas is
widely used in luminous signs.
7. Nearly 1% of
the earth's atmosphere is...
9. About 21% of
the earth's atmosphere is...
10. Most of the
visible universe is made of…
11. This gas is
used in strobe lights
Down
1.When combined with tin, this gas helps
keep your teeth strong.
3. This gas helps
keep swimming pools clean.
5. About 78% of
the earth's atmosphere is...
8. A radioactive
gas