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2 years ago

How many sig figs in each? -27.43 -1.90 -101

Chemistry

1 answer:

GarryVolchara [31]2 years ago

5 0

1. Has 4 sig figs, all non zeros are significant
2. 3 sig figs trailing zero after a decimal
3. 3 sig figs

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1. An electric power plant uses energy from burning coal to generate steam at 450 °C. The plant is cooled by 20 °C water

kap26 [50]

Answer:

Explanation:

Efficiency of the electric power plant is $e=1-\frac{T_{2}}{T_{1}}$

Here Temperature of hot source $T_{1} = 450^{o}C=450+273=723 K$

and Temperature of sink $T_{1} = 20^{o}C=20+273=293 K$

Hence the efficiency is $e=1-\frac{293}{723}=0.5947=59.47%$

Now another formula for thermal efficiency Is

$e_{therm}=\frac{Q_{1}-Q_{2}}{Q_{1}}=\frac{W}{Q_{1}}$

Here QI is the of heat taken from source 100 MJ ; Q2 of heat transferred to the sink (river) to be found

W is the of work done and W = QI -Q2

Hence From $e_{therm}=\frac{Q_{1}-Q_{2}}{Q_{1}}=\frac{W}{Q_{1}}$

$W=e(Q_{1})=(0.5947)(100)=59.47MJ$

Hence the of heat transferred to the river Is $Q_{2} -W = (100 -59.47=40.53$

6 0

3 years ago

Chem help what's the answer to 8 and why will give brainliest

laiz [17]

avogadros law states that under constant temp n pressure, volume of a gas is directly proportional to amount of gas

amount of gas1 = 352millimoles

amount of gas2 = 352+100 = 452millimoles

new vol = old vol x 452/352 = 25.2 x 452/352

= 32.4 mL

4 0

3 years ago

Read 2 more answers

A beaker in your laboratory drawer has an inside diameter of 6.8 cm and a height of 8.9 cm. Using the equation V= arh, calculate

olga_2 [115]

Answer:

323.22 ml

Explanation:

Given that :

Diameter, d = 6.8cm

Height, h = 8.9cm

V = arh

Recall :

Volume, V = πr²h

Radius, r = diameter / 2 = 6.8 / 2 = 3.4cm

V = π * 3.4^2 * 8.9

V = 323.21961 cm³

Recall:

1ml = 1cm³

Hence,

323.21961 cm³ = 323.21961 ml

Volume = 323.22 ml

4 0

2 years ago

A student is reading the volume from a standard 50-mL buret identical to what you used in the lab. The bottom of the meniscus is

Nutka1998 [239]

Answer:

20 mL

Explanation:

<em>The student should record 20 mL as the correct volume.</em>

The curved surface of a liquid that is usually observed in a buret is referred to as the meniscus. This meniscus is created as a result of the surface tension of the liquid against the walls of the buret. <u>Hence, in order to avoid errors due to parallax, the bottom of the meniscus should be read and not the top.</u>

Therefore, the correct volume that the student should record is 20 mL.

8 0

3 years ago

What is the main pigement for photosyenthesis inchloroplasts

Ilya [14]

I assume the answer is chlorophyll (a or b) but could also be carotenoids.

3 0

2 years ago