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BlackZzzverrR [31]
2 years ago
10

How many electrons elements are present in period 2 ?​

Chemistry
2 answers:
katrin2010 [14]2 years ago
7 0
There are 8 elements
AVprozaik [17]2 years ago
3 0
There are Eight elements
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Minerals are very useful to us. Which of the following is a false statement? Question options: Pyrite is an ore of gold and is u
lilavasa [31]

Answer:

The false statement is :

  • Pyrite is an ore of gold and is used in jewelry making.
  • Cobalt is not used in medicine.

Explanation:

Pyrite is an ore of iron sulfide found on the Earth and in coal, limestone and in many deposits of metallic ores. Due to its luster and pale yellowish color it appears as gold due to which it is also termed as Fool's gold.

It is used in firearms , in production of sulfur dioxide gas, etc.

Cobalt is used as medicine to treat cancer patient. Co-60 is used in treatment of cancer in which gamma rays produced by Co-60 are used  to kill tumor cells in a cancer patient.

Where as talc is used in industries like : paper making, food, paints, plastics etc. Quartz is primary material used to prepare glass and cobalt is used as

4 0
3 years ago
Which two types of weather are most likely to occur when you see clouds Like these?
katen-ka-za [31]

Answer:

A: Sunshine

Explanation:

6 0
2 years ago
Read 2 more answers
A 2.04 g lead weight, initially at 10.8 oC, is submerged in 7.74 g of water at 52.2 oC in an insulated container. clead = 0.128
QveST [7]

Answer:

Explanation:

Hello, in this case, the lead is catching heat and the water losing it, that's why the heat relation ship is (D is for Δ):

DH_{lead}=-DH_{water}

Now, by stating the heat capacity definition:

m_{Pb}C_{Pb}*(T_{eq}-T_{lead}=-m_{H_2O}C_{H_2O}*(T_{eq}-T_{H_2O})\\

Solving for the equilibrium temperature:

T_{eq}=\frac{m_{Pb}C_{Pb}T_{Pb}+m_{H_2O}C_{H_2O}T_{H_2O}}{m_{Pb}C_{Pb}+m_{H_2O}C_{H_2O}} \\\\T_{eq}=\frac{2.04g*0.128J/(g^oC)*10.8^oC+7.74g*4.18J/(g^oC)*52.2^oC}{2.04g*0.128J/(g^oC)+7.74g*4.18J/(g^oC)} \\\\T_{eq}=51.87^oC

Which is very close to the water's temperature since the lead's both mass and head capacity are lower than those for water.

Best regards.

5 0
2 years ago
A student receives 83.2 points, 44.6 points, 74.4 points, and 52.3 points on each of four tests. Determine the student's test av
kow [346]

Answer:

The average is 63.6

Explanation:

<u>Step 1: Calculate the total points of all tests together</u>

The total of the 4 tests is : 83.2 points + 44.6 points + 74.4 points + 52.3 points = 254.5 points

<u>Step 2: Calculate the average points</u>

We have 4 tests so we divide the total number by 4

254.5 points  / 4 = 63,625 points

<u>Step 3: take significant digits into account</u>

<em><u>Sum or difference :</u></em><u> </u>Add or subtract in the normal way, then round the answer to the LEAST number of places to the decimal point of any number in the problem

⇒ in this case : 83.2 + 44.6 + 74.4 + 52.3 = 254.5

<u>Multiplication and division:</u> the answer is reported in such a way that it reflects the reliability of the least precise operation. Your answer cannot be MORE precise than the least precise measurement.

254.5 / 4 = 63.6

3 0
3 years ago
Glass is a mixture but not a compound . explain​
timofeeve [1]

Answer:

A mixture is just a combination of things, like air (made up of different but distinct gasses), or toothpaste, where compounds are physically mixed together but stay fundamentally what they started as. If there is a chemical change, like hydrogen and chlorine gas reacting to form hydrochloride acid, then it is known as a new compound.

5 0
3 years ago
Read 2 more answers
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