Which of the following is a homogeneous mixture? gasoline vegetable oil and wate

Question

Which of the following is a homogeneous mixture? gasoline vegetable oil and water sugar dissolved in water A and C A, B, and C The number of significant figures in 0.066900 times 10^-4 is 5 6 7 3 4 What is the correct answer to the following expression? 4.13 times 10^-l0 7.59 times 10^-12 4.21 times 10^-10 4.2 times 10^-10 4 times 10^-10 4.206 times 10^-10 4.2059 times 10^-10 How many 150-mg aspirin tablets can be made from 15.0 kg of aspirin? 100,000 1,000,000 10000 10,000 10,000,000 The daily dietary energy requirement for an adult is 2.00 times 10^3 kcal (1 ca = 4.184 J). This is equivalent to 47.8 times 10^4 kJ. 8.37 times 10^3 kJ 8.37 times 10^3 J. 2.00 times 10^3 kJ. 478 kJ.

Explanation / Answer

1(c): A homogeneous mixture has uniform properties throughout the solution. In such a case, gasoline is a mixture of petroleum products that form homogeneous mixture. In sugar solution, it is a true solution in which sugar and water are not seen separately. They form a single entity. Hence these 2 are homogeneous mixtures.

2(a): Zeroes appearing in front of non-zero digits are not significant. All digits expressed before the exponential term are significant. In this case 0.066900 x 10-4, the zeroes before 6 are not significant. Before this exponential term 10-4, there are 5 significant digits 6,6,9,0,0. Hence there are 5 significant figures.

3(a): 4.13 x 10-10 + 7.59 x 10-12

There are 3 significant digits in each term. To make the powers of 10 equal in both cases, for 7.59 x 10-12, multiply and divide the term by 100 as

(7.59 x 10-12 x 100)/100 = 7.59 x 10-10/100 = 0.0759 x 10-10

Now on adding, 4.13 x 10-10 + 0.0759 x 10-10 = 4.2059 x 10-10

Rounding off to 3 significant figures, 4.21 x 10-10

4(a): Number of aspirin tablets = Total quantity(mass) of aspirin available/Mass of 1 aspirin tablet

= 15.0kg/150mg = 15.0 x 106 mg/150 mg

=106/10 = 105 tablets.

The number of tablets that can be made are 100,000

5(b): 2.00 x 103 kcal = 2.00 x 103 x 103 cal (conversion factor kcal = 103 cal)

Converting to Joules, 2.00 x 103 x 103 x 4.184 = 8.368 x 106 J

This can be written as 8.368 x 103 kJ. Rounding off to 3 significant digits, 8.37 x 103 kJ

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