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3 years ago

What is 57.048 rounded to three significant figures?

1 answer:

4 0

57.0 is it rounded to three sig figs. You count three spaces then round from there, which would be the zero and you would round down because the four is there.

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A piece of lumber is 7.60cm long. What is it’s length in millimetres and in inches?

MrRissso [65]

Explanation:

Since 10mm is 1cm

Therefore 7.60cm is 760mm

Since 1 inch is 2.54cm

Therefore 7.60cm is 3.10 inches

4 0

1 year ago

A compound has an empirical formula of AB and a molar mass of 90 g/mol. What is its

Lelu [443]

Answer:

A3B3

Explanation:

Molecular formula = n x empirical formula

(AB) n = 90

MM of AB = 30 g/mol

30n = 90

Divide both side by the coefficient n i.e 30

n = 90/30 = 3

Molecular formula = n x empirical formula

Molecular formula = n x (AB)

Molecular formula = 3(AB) = A3B3

8 0

2 years ago

5.11 g of MgSO₄ is placed into 100.0 mL of water. The water's temperature increases by 6.70°C. Calculate ∆H, in kJ/mol, for the

cupoosta [38]

Answer: Thus ∆H, in kJ/mol, for the dissolution of MgSO₄ is -66.7 kJ

Explanation:

To calculate the entalpy, we use the equation:

$q=mc\Delta T$

where,

q = heat absorbed by water = ?

m = mass of water = ${\text {volume of water}}\times {\text {density of water}}=100.0ml\times 1.00g/ml=100.0g$

c = heat capacity of water = 4.186 J/g°C

$\Delta T$ = change in temperature = $6.70^0C$

$q=100.0g\times 4.184J/g^0C\times 6.70^0C=2803.3J=2.8033kJ$

Sign convention of heat:

When heat is absorbed, the sign of heat is taken to be positive and when heat is released, the sign of heat is taken to be negative.

The heat absorbed by water will be equal to heat released by $MgSO_4$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Given mass = 5.11 g

Molar mass = 120 g/mol

Putting values in above equation, we get:

$\text{Moles of }MgSO_4=\frac{5.11g}{120g/mol}=0.042mol$

0.042 moles of $MgSO_4$ releases = 2.8033 kJ

1 mole of $MgSO_4$ releases = $\frac{2.8033 kJ}{0.042}\times 1=66.7kJ$

Thus ∆H, in kJ/mol, for the dissolution of MgSO₄ is -66.7 kJ

3 0

3 years ago

Thirsty Thursday:) post your celebrity crush Or post your favorite drink :)

Nata [24]

Answer:

My celebrity crush is young Keanu Reeves and my favorite drink is matcha tea

Explanation:

7 0

2 years ago

A cube has a length of 1.02 cm and a mass of .001012 kg what is its density

slega [8]

Answer:

d = 9.5× 10⁻⁴ Kg/cm³

Explanation:

Given data:

Length of cube = 1.02 cm

Mass of cube = 0.001012 Kg

Density of cube = ?

Solution:

The length , height and width of cube is always same. Thus the volume of cube is,

Volume = length × height× width

Volume = 1.02 cm × 1.02 cm × 1.02 cm

Volume = 1.06 cm³

Density of cube:

d = 0.001012 Kg /1.06 cm³

d = 9.5× 10⁻⁴ Kg/cm³

8 0

3 years ago