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3 years ago

What would be the mass of a sample containing 0.7 mol of pure tungsten?. . 0.04 g. . 51.8 g. . 128.7 g. . 262.6 g.

Physics

2 answers:

Oksana_A [137]3 years ago

7 0

Answer:

Option C is the correct answer.

Explanation:

Standard atomic mass of tungsten = 183.84 u

1 u = 1.66 x 10⁻²⁴ g

1 mol = 6.02 x 10²³ atoms

Mass of 0.7 mol tungsten = 0.7 x 6.02 x 10²³ x 183.84 x 1.66 x 10⁻²⁴ = 128.7 g

Mass of 0.7 mol tungsten = 128.7 g

Option C is the correct answer.

mojhsa [17]3 years ago

4 0

There are several information's of immense importance already given in the question. The answer to the question can be easily determined using those available information's.

Mr of pure tungsten = 183.84
Mass of tungsten = Mole * Mr
= 0.7 * 183.84
= 128.7 gm
From the above deduction, it can be concluded that the correct option among all the options that are given in the question is the third option or the penultimate option.

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3 years ago

The resistance and the magnitude of the current depend on the path that the current takes. The drawing shows three situations in

maria [59]

Answer: (a). Resistance = 0.4286ohms and Current (I) = 7A

(b). Resistance (R) = 0.027 ohms and Current (I) = 111.1A

(c). Resistance (R) = 0.1071 ohms and Current (I) = 28A

Explanation:

From the question, given that;

ρ = 1.5*10-2ῼ.m

Lo = 7cm = 0.07m

V = 3V

From the formula R = ρL/A, where A is the area of cross section, L is the length of material and ρ is the resistivity.

(A)

L = 4Lo and A = 2Lo*Lo

R = ρL/A

R = ρ4Lo/(2Lo*Lo)

R = 2ρ /Lo = 2*1.5*10-2/0.07

R = 0.4286 ῼ

From this the current becomes;

I = V/R = 3/ 0.4286 = 6.99 = 7A

(B)

L = Lo and A = 4Lo * 2Lo

R = ρL/A

R = ρLo/ (4Lo*2Lo) after eliminating Lo from both sides we get,

R = ρ/8Lo = 1.5*10-2 / 8*0.07

R = 0.027

Current (I) = V/R = 3/0.027 = 111.1A

(C)

L = 2Lo and A = Lo * 4Lo

R = ρL/A

R = ρ2Lo/ (Lo*4Lo) eliminating Lo from both sides we get,

R = ρ/2Lo = 1.5*10-2 / 2*0.07 = 0.1071

The current becomes;

I = V/R = 3/0.1071 = 28A

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4 years ago

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3 years ago

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3 years ago

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3 years ago