The volume of the textbook calculated by the student written to 3 significant figures is 992cm³
- According to this question, a student calculates the volume of his textbook and arrived at an answer of 991.880 cm³.
- To round up this digit to 3 significant figures, which means that only 3 significant numbers should appear in the answer.
- To do this, the number after the third number is 8, which means we can round up the value of 1 to 2. Hence, the volume of the textbook calculated by the student is 992cm³ in 3 s.f.
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Answer : The molal freezing point depression constant of X is 
Explanation : Given,
Mass of urea (solute) = 5.90 g
Mass of X liquid (solvent) = 450.0 g
Molar mass of urea = 60 g/mole
Formula used :

where,
= change in freezing point
= freezing point of solution = 
= freezing point of liquid X= 
i = Van't Hoff factor = 1 (for non-electrolyte)
= molal freezing point depression constant of X = ?
m = molality
Now put all the given values in this formula, we get
![[0.4-(-0.5)]^oC=1\times k_f\times \frac{5.90g\times 1000}{60g/mol\times 450.0g}](https://tex.z-dn.net/?f=%5B0.4-%28-0.5%29%5D%5EoC%3D1%5Ctimes%20k_f%5Ctimes%20%5Cfrac%7B5.90g%5Ctimes%201000%7D%7B60g%2Fmol%5Ctimes%20450.0g%7D)

Therefore, the molal freezing point depression constant of X is 
A grounding electrode is any object that directly links to the earth. They are most times used to divert electricity from the elements.
- Swimming pool structures and structural <u>reinforcing steel. 250.52(B)(3)</u><u>,</u> [680.26(B)(1), and (B)(2)] shall not be used as a grounding electrode.
In code 250.52(B)(3) it is clearly specified that the bonding grid and reinforcing steel that is related to a pool should not be used as grounding electrodes.
This is essential because when a metal that lies beneath a swimming pool is used as a grounding electrode, current from nearby electrical systems can be introduced into the pool.
This could cause the electrocution of anybody in the swimming pool at that time.
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Heat
gained or loss in a system can be calculated by multiplying the given mass to the
specific heat capacity of the substance and the temperature difference. It is
expressed as follows:<span>
Heat = mC(T2-T1)
When two objects are in contact,
it should be that the heat lost is equal to what is gained by the other. So, the heat released by the lead is equal to the heat that is absorbed by the water.
</span>Heat = mC(T2-T1) = 50.0 mL (1.00 g/mL) (4.18 J/g °C) (20 °C - 18 °C) = 418 J<span>
</span>
Answer:
C. That atoms made up the smallest form of matter
Explanation:
The crux of the Dalton's atomic theory is that atoms are the smallest form of matter. He propositioned that atoms is an indivisible particle and beyond an atom, no form of matter exists.
Series of discoveries through time have greatly shaped the Dalton's atomic theory. The discovery of cathode rays by J.J Thomson in 1897 opened up the atom. Atoms were now seen to be made up of some negatively charged particles. Ernest Rutherford through his gold foil experiment proposed the nuclear model of the atom.