💡Okay, so I need to find the mass percentage of oxygen in chromic acid. First, I should figure out what chromic acid is. I think it's a chemical compound, and I remember that acids usually have "ic" in their names, like sulfuric acid or nitric acid. So chromic acid must be related to chromium. I recall that chromium has different oxidation states, and in chromic acid, it's probably in a higher oxidation state because it's an acid. Maybe it's Cr(VI) since that's common in chromic acid. Now, what's the chemical formula for chromic acid? I think it's H2CrO4. Let me double-check that. Yeah, I think that's right: two hydrogens, one chromium, and four oxygens.Next, I need to find the molar mass of chromic acid to determine the mass percentage of oxygen. Molar mass is the sum of the atomic masses of all the atoms in the molecule. So, I'll need the atomic masses of hydrogen, chromium, and oxygen.Hydrogen has an atomic mass of about 1.008 g/mol, chromium is around 52.00 g/mol, and oxygen is approximately 16.00 g/mol. So, for H2CrO4:- Hydrogen: 2 atoms × 1.008 g/mol = 2.016 g/mol- Chromium: 1 atom × 52.00 g/mol = 52.00 g/mol- Oxygen: 4 atoms × 16.00 g/mol = 64.00 g/molAdding these up: 2.016 + 52.00 + 64.00 = 118.016 g/molNow, the total mass of oxygen in chromic acid is 64.00 g/mol. To find the mass percentage of oxygen, I'll divide the mass of oxygen by the molar mass of chromic acid and then multiply by 100.So, mass percentage of oxygen = (64.00 / 118.016) × 100 ≈ 54.23%Wait, does that make sense? Let me check my calculations again. 2 hydrogens at 1.008 each is about 2.016, chromium is 52, and four oxygens at 16 each is 64. Adding them up gives 118.016, which seems right. Then, 64 divided by 118.016 is approximately 0.5423, and multiplying by 100 gives about 54.23%. Yeah, that seems correct.I think I've got it. The mass percentage of oxygen in chromic acid is approximately 54.23%.

💡First, calculate the total data used over the 4-week period by adding the data used each week: 2 GB + 3 GB + 5 GB + 10 GB = 20 GB.Next, determine how much data Charlie used over his 8 GB limit: 20 GB - 8 GB = 12 GB over the limit.Finally, calculate the cost per GB over the limit by dividing the extra cost by the number of GB over the limit: 120 / 12 GB = 10 per GB.

💡First, I need to find the prime factorization of 2520. I'll start by dividing the number by the smallest prime, which is 2.2520 divided by 2 is 1260. 1260 divided by 2 is 630. 630 divided by 2 is 315. Now, I'll move to the next prime number, which is 3. 315 divided by 3 is 105. 105 divided by 3 is 35. Next, I'll divide by 5. 35 divided by 5 is 7. Finally, I'll divide by 7. 7 divided by 7 is 1. So, the prime factorization of 2520 is (2^3 cdot 3^2 cdot 5 cdot 7).To find the number of distinct positive factors, I'll use the formula that involves adding 1 to each of the exponents in the prime factorization and then multiplying these together.For the exponent of 2, which is 3, I add 1 to get 4. For the exponent of 3, which is 2, I add 1 to get 3. For the exponent of 5, which is 1, I add 1 to get 2. For the exponent of 7, which is 1, I add 1 to get 2.Now, I'll multiply these together: (4 times 3 times 2 times 2 = 48).Therefore, 2520 has 48 distinct positive factors.

💡First, let's denote the original number of students in the class as ( N ).The average age of the class before the new students joined is 40 years, so the total age of the original class is:[ T = 40N ]When 12 new students join, the total number of students becomes ( N + 12 ), and the total age of the class becomes:[ T + 12 times 32 ]The new average age of the class after the new students join is 36 years. Therefore, we can write the equation:[ T + 12 times 32 = 36(N + 12) ]Substituting the value of ( T ) from the first equation into the second equation:[ 40N + 384 = 36N + 432 ]Solving for ( N ):[ 40N - 36N = 432 - 384 ][ 4N = 48 ][ N = frac{48}{4} ][ N = 12 ]So, the original strength of the class was 12 students.

💡To estimate the total population of all the cities in the County of Maplewood, we start by noting that there are 25 cities. The average population per city is given to be between 6,200 and 6,800. First, we calculate the midpoint of the given range to find an approximate average population per city:[text{Average population} = frac{6,200 + 6,800}{2} = 6,500]Next, we use this average population to estimate the total population of all 25 cities:[text{Total population} = 25 times 6,500 = 162,500]Thus, the estimated total population of all the cities in the County of Maplewood is 162,500.

💡First, determine the time it takes for Jamshid to paint the fence alone. Since Jamshid can paint the fence in 50% less time than Taimour, and Taimour takes 18 hours, Jamshid takes half of that time:[frac{18}{2} = 9 text{ hours}]Next, calculate their individual work rates. Taimour's work rate is:[frac{1}{18} text{ of the fence per hour}]Jamshid's work rate is:[frac{1}{9} text{ of the fence per hour}]Combine their work rates to find the total work rate when working together:[frac{1}{18} + frac{1}{9} = frac{1}{18} + frac{2}{18} = frac{3}{18} = frac{1}{6} text{ of the fence per hour}]Finally, determine the time it takes for them to paint the fence together by taking the reciprocal of their combined work rate:[frac{1}{frac{1}{6}} = 6 text{ hours}]