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2 years ago

Determine the length of the object shown A. 97.8 mmB. 97.80 mmC. 97 mmD. 98 mm

Chemistry

1 answer:

jeka942 years ago

6 0

Answer:

A. 97.8 mm

Explanation:

There are 10 divisions between 9 cm (90 mm) and the end of the ruler (10 cm or 100 mm).

Each division equals 1 mm.

Each 5 mm mark has a longer tick, and the dashed red line is between the 97 mm and 98 mm marks.

You would normally estimate to the nearest tenth of a division. An estimate of 0.8 mm is reasonable.

The length of the object is 97.0 mm + 0.8 mm = 97.8 mm.

B is wrong. You can't possibly estimate to the nearest hundredth of a division.

C is wrong. The dashed red line slightly before the 98 mm mark.

D is wrong. If the dashed red line were exactly on the 98 mm mark, you would record the measurement as 98.0 mm. This indicates that you measured the object to zero tenths on either side of the mark.

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It is a solution, because it's the alloy of tin and copper

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3 years ago

I need help solving this!

zmey [24]

Answer: Moles of hydrogen required are 4.57 moles to make 146.6 grams of methane, $CH_{4}$ .

Explanation:

Given: Mass of methane = 146.6 g

As moles is the mass of a substance divided by its molar mass. So, moles of methane (molar mass = 16.04 g/mol) are calculated as follows.

$Moles = \frac{mass}{molar mass}\\= \frac{146.6 g}{16.04 g/mol}\\= 9.14 mol$

The given reaction equation is as follows.

$C + 2H_{2} \rightarrow CH_{4}$

This shows that 2 moles of hydrogen gives 1 mole of methane. Hence, moles of hydrogen required to form 9.14 moles of methane is as follows.

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3 years ago

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3 years ago

Materials expand when heated. Consider a metal rod of length L0 at temperature T0. If the temperature is changed by an amount ΔT

marysya [2.9K]

Answer:

(a) The length at temperature 180°C is 40.070 cm

(b) The length at temperature 90°C is 64.976 inches

Explanation:

(a) The given parameters are

The thermal expansion coefficient, α for steel = 1.24 × 10⁻⁵/°C

The initial length of the steel L₀ = 40 cm

The initial temperature, t₀ = 40°C

The length at temperature 180°C = L

Therefore, from the given relation, for change in length, ΔL, we have;

ΔL = α × L₀ × ΔT

The amount the temperature changed ΔT = 180°C - 40°C = 140°C

Therefore, the change in length, ΔL, is found as follows;

ΔL = α × L₀ × ΔT = 1.24 × 10⁻⁵/°C × 40 × 140°C = 0.07 cm

Therefore, L = L₀ + ΔL = 40 + 0.07 = 40.07 cm

The length at temperature 180°C = 40.07 cm

(b) Given that the length at T = 120°C is 65 in., we have;

The temperature at which the new length is sought = 90°C

The amount the temperature changed ΔT = 90°C - 120°C = -30°C

ΔL = α × L₀ × ΔT = 1.24 × 10⁻⁵/°C × 65 × -30°C = -0.024375 inches

The length, L at 90°C is therefore, L = L₀ + ΔL = 65 - 0.024375 = 64.976 in.

The length at temperature 90°C = 64.976 inches

Therefore;

L = 60 + α × 60 × (T - 150°C)

L = 60 + α × 60 × T - 9000 × α

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7 0

3 years ago

Please, can i get some help with these question? Can anyone please answer what exactly i should write?

pav-90 [236]

Use photomath. I would really recommend it! Hope this helps!

8 0

3 years ago

Read 2 more answers

Determine the length of the object shown A. 97.8 mmB. 97.80 mmC. 97 mmD. 98 mm​

Determine the length of the object shown A. 97.8 mmB. 97.80 mmC. 97 mmD. 98 mm