Can anyone help with number 8.

What is a problem that would likely occur if two cultures had different calenderars

aksik [14]

The Sun, Moon, and stars have helped people for thousands of years. When you look into the sky, you will notice that they follow certain patterns. This happens most of the time, but not all of the time. Since most patterns repeat over and over, they have helped us keep track of time. These patterns have also helped us make calendars. Making calendars was a difficult task. Our ancestors had to decide on the length of a year. Also, they had to decide on the length of a day. As you know a day takes 24 hours. That is the time that Earth takes to rotate once on its axis. A year is longer and takes 365 days. This length of time is related to the time that it takes for Earth to go around the Sun. However, this is not exactly true. Earth’s trip takes 365 days – plus a fraction of another day. This is what complicates our calendar. We have been able to solve this problem by adding an extra day in the month of February. Most often, you will see that February has 28 days. Every four years, February has one extra day. During this year we end up with 29 days in this month. When this happens, the year is called a Leap Year. It helps us keep our calendar in order. Deciding on the length of a month has also been a challenge. Some cultures around the world have used a lunar calendar. A lunar calendar is based on the Moon’s cycle. The Moon takes 29 and one-half days to complete one cycle. Then things got a lot harder. Different cultures start their months at a different time of the Moon’s cycle. For example, the Hebrew and Islamic calendars start their months when a crescent moon is seen in the sky. The Chinese start their new months at the new moon phase. These differences have made it harder for cultures to communicate. Trading with one another has also been hard for this reason. As time went by, most countries began to use the same calendar. When this happened in the twentieth century, trade and communication became a lot easier. Some countries decided to drop thirteen days from their calendar. This is because their old way of counting did not match up with the new way. England had problems with the calendar back in the 1500s. The English decided to divide their calendar into months. Each month had four weeks. By doing this, one week ended up being longer than seven days. Also, this resulted in thirteen months to a yea

3 0

3 years ago

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What is the number of electrons in the highest occupied energy level of an element in Group 5A?

nignag [31]

5 is the answer i took the test

8 0

2 years ago

Which substance is the oxidizing agent in the following reaction? Fe2S3 + 12HNO3 → 2Fe(NO3)3 + 3S + 6NO2 + 6H2O Which substance

aleksandr82 [10.1K]

Answer:

HNO3 is the oxidizing agent

Explanation:

Step 1:

The oxidizing agent is responsible to oxidize another. but itself undergoes a reduction .

Fe2S3:

Fe has an oxidation number of +3

S has an oxidation number of -2

HNO3:

O has an oxidation number of -2 ( we have 3 times O so this makes -6)

H has an oxidation number of +1

N has an oxidation number of +5

Fe(NO3)3

O has an oxidation number of -2 ( we have 3 times O so this makes -6)

Fe has an oxidation number of +3

Since NO3 has an oxidation number of -1; N has an oxidation number of +5

S alone has an oxidation number of 0

NO2:

O has an oxidation number of -2 (we have 2 times O, this makes -4)

N has an oxidation number of +4

Fe doesn't change from oxidation number. It stays +3

N goes from +5 to +4 → this is a reduction

S goes from -2 to 0 → this is an oxidation

The reducing agent is the compound that contributes the oxidized species (S).

The oxidizing agent contributes the reducing species (N)

The answer is HNO3

5 0

2 years ago

What is the relationship between the reactant and yield

solong [7]

Yield is the measured amount of a product obtained from a reaction.

Hope that's helpful

7 0

3 years ago

Determine the limiting reactant (lr) and the mass (in g) of nitrogen that can be formed from 50.0 g n2o4 and 45.0 g n2h4. some p

Licemer1 [7]

N2O4(l) + 2 N2H4(l) → 3 N2(g) + 4 H2O(g)
1) to calculate the limiting reactant you need to pass grams to moles.
 moles is calculated by dividing mass by molar mass

mass of N2O4: 50.0 g
molar mass of N2O4 = 92.02 g/mol
molar mass of N2H4 = 32.05 g/mol.
mass of N2H4:45.0 g

moles N2O4=50.0/92.02 g/mol= 0,54 mol of N2O4
moles N2H4= 45/32.05 g/mol= 1,40 mol of N2H4

 2)
By looking at the balanced equation, you can see that 1 mol of N2O4 needs 2 moles of N2H4 to fully react . So to react 0,54 moles of N2O4, you need 2x0,54 moles of N2H4 moles
N2H4 needed = 1,08 moles.
You have more that 1,08 moles N2H4, so this means the limiting reagent is not N2H4, it's N2O4. The molecule that has molecules that are left is never the limiting reactant.

3) 1 mol of N2O4 reacting, will produce 3 mol of N2 (look at the equation)
There are 0,54 mol of N2O4 available to react, so how many moles will produce of N2?
1 mol N2O4------------3 mol of N2
0,54 mol N2O4--------x
x=1,62 mol of N2

4) the only thing left to do is convert the moles obtained, to grams.
We use the same formula as before, moles equal to mass divided by molar mass.
$moles= \frac{grams}{molar mass}$ (molar mass of N2= 28)
1,62 mol of N2= mass/ 28
mass of N2= 45,36 grams

4 0

3 years ago