is 7 cus the valance electron for sodium is Ne 3s1 and for chlorine is Ne 3s13p5
dinosaur footprint
Explanation:
A dinosaur footprint is an example of a trace fossil. A trace fossil is a type of fossil that shows the activities of organisms that lived in the past.
- Fossils are the preserved remains of organisms that lived several years ago.
- Fossils are usually found in sedimentary rocks and thick layers of ice in temperate and polar regions.
- Body fossils are the remains of the body parts of an organism that has been preserved. They can be skeletal parts, teeth, eggs e.t.c
- A trace fossil shows the preserved remains of the activities of an organism.
- They can be fingerprints, burrows and borings, feccal pellets e.t.c
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Answer: The new volume at different given temperatures are as follows.
(a) 109.81 mL
(b) 768.65 mL
(c) 18052.38 mL
Explanation:
Given:
= 571 mL, 
(a) 
The new volume is calculated as follows.

(b) 
Convert degree Fahrenheit into degree Cesius as follows.

The new volume is calculated as follows.

(c) 
The new volume is calculated as follows.

<span>The student should
follow following steps to make 1 L of </span>2.0 M CaCl₂.<span>
<span>
1. First he should
calculate the number of moles of 2.0 M CaCl</span></span>₂ in 1 L solution.<span>
</span>Molarity of the solution = 2.0 M<span>
Volume of solution which should be prepared = 1 L
Molarity =
number of moles / volume of the solution
Hence, number of moles in 1 L = 2 mol
2. Find
out the mass of dry CaCl</span>₂ in 2 moles.<span>
moles =
mass / molar mass
Moles of CaCl₂ =
2 mol</span><span>
Molar mass of CaCl₂ = </span><span>110.98 g/mol
Hence, mass of CaCl</span>₂ = 2 mol x <span>110.98 g/mol
= 221.96
g
3. Weigh the mass
accurately
4. Then take a cleaned and dry1 L volumetric flask and place a funnel top of it. Then carefully add the salt into the volumetric flask and
finally wash the funnel and watch glass
with de-ionized water. That water also should be added into the volumetric
flask.
5. Then add some
de-ionized water into
the volumetric flask and swirl well until all salt are
dissolved.
<span>6. Then top up to
mark of the volumetric flask carefully.
</span></span>
7. As the final step prepared solution should be labelled.