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klasskru [66]
3 years ago
14

Select the correct answer. What is the SI unit of time?

Chemistry
2 answers:
photoshop1234 [79]3 years ago
7 0

Option A: second

SI units are international system of units. This is defined as a system of units of physical quantities such as mass, length, temperature, current etc. Some of the physical units are gram, meter, second etc. along with the set of prefixes which indicates the multiplication and division with some power of 10.

For same physical quantities, these units are inter convertible For example,

1 g=10^{-3}kg

and,

1 g=10^{3}mg

Here, g (gram), kg (kilogram) and mg (milligram) all are units of mass.

The units of time are second, minute, hour, day and year. Here, second is the SI unit and all the units are inter convertible as  follows:

1 year=365 days

1 day=24 hours

1 hour=60 minutes

1 minute-60 seconds

Thus, the SI unit of time is second.


Leni [432]3 years ago
5 0

Answer:

A. second

Explanation:

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what is the percent yield of NaCl if 31.0 g of CuCl reacts with excess NaNo3 to produce 21.2 g of NaCl
olchik [2.2K]
Percentage Yield = (Actual Yield ÷ Theoretical Yield) × 100  

The Actual Yield is given in the question as 21.2 g of NaCl.  However, in order to find the theoretical yield, you have to write a balanced equation and use the mole ratio to calculate the mass of NaCl that would be produced.

Balanced Equation:   CuCl + NaNO₃    →    NaCl + CuNO₃

Moles of CuCl = Mass of CuCl ÷ Molar Mass of CuCl
                         =  31.0 g ÷ (63.5 + 35.5)g/mol
                         = 0.31 mol

the mole ratio of CuCl to NaCl is 1  :  1,
∴ if moles of CuCl = 0.31  mol,

then moles of NaCl = 0.31 mol

Now, Mass of NaCl = Moles of NaCl × Molar Mass of NaCl
                                 =  0.31 mol × (23 + 35.5) g/mol
                                 =  18.32 g

⇒ the THEORETICAL Yield of NaCl, in this case, is 18.32 g.

Now, since Percentage Yield = (Actual Yield ÷ Theoretical Yield) × 100  

⇒ Percentage Yield of NaCl = (21.2g ÷ 18.32g) × 100  
                                                = 115.7 %


NOTE: Typically, the percentage yield of a reaction is less than 100%, however in a case where the mass of the substance is weighed with impurities, then that mass may be in excess of 100% as seen here.
4 0
3 years ago
ASAP: The main difference between the gravitational force and electrical force is that
Dahasolnce [82]

Answer:

Electrical force can pull and push

Explanation:

5 0
3 years ago
Geologists may choose to lick a mineral to identify it. What mineral is the geologist expecting with this test?
Archy [21]
<span>NaCl (halite) or KCl (sylvite) </span>
8 0
3 years ago
The volume of the earth is approximately 1.08326x10 to the 12th power km to the 3rd power. How many liters is this
mafiozo [28]

Here, we are required to determine the volume of the earth which is 1.08326 × 10¹² km³ in liters.

<em>The volume of the earth is approximately</em>,

, 1.08326 × 10²⁴ liters

By conversion factors;

  • <em>1dm³ = 1liter</em>
  • However; <em>1km = 10000dm = 10⁴ </em><em>dm</em>
  • Therefore, 1km³ = (10⁴)³ dm³.

Consequently, 1km³ = 10¹²dm³ = 10¹²liters.

The conversion factor from 1km³ to liters is therefore, c.f = 10¹²liters/km³

Therefore, the volume of the earth which is approximately, 1.08326 × 10¹² km³ can be expressed in liters as;

<em>1.08326 × 10¹² km³ × 10¹²liters/km³ </em>

The volume of the earth is approximately,

1.08326 × 10²⁴ liters.

Read more:

brainly.com/question/16814684

7 0
2 years ago
20.00 g of aluminum (Al) reacts with 78.78 grams of molecular chlorine (Cl2), all of each reaction is completely consumed and as
shepuryov [24]

The reaction forms 98.76 g AlCl_3.  

We have the masses of two reactants, so this is a <em>limiting reactant problem</em>.

We know that we will need a balanced equation with masses, moles, and molar masses of the compounds involved.  

<em>Step 1. Gather all the information</em> in one place with molar masses above the formulas and everything else below them.  

M_r: ___26.98 _70.91 __133.34

________2Al + 3Cl_2 → 2AlCl_3

Mass/g: 20.00 _78.78

<em>Step 2</em>. Calculate the <em>moles of each reactant</em>  

Moles of Al = 20.00 g Al × (1 mol Al /26.98 g Al) = 0.741 29 mol Al

Moles of Cl_2 = 78.78 g Cl_2 × (1 mol Cl_2 /70.91 g Cl_2) = 1.11 10 mol Cl_2

Step 3. Identify the <em>limiting reactant</em>  

Calculate the moles of AlCl_3 we can obtain from each reactant.  

<em>From Al</em>: Moles of AlCl_3 = 0.741 29 mol Al × (2 mol AlCl_3/2 mol Al) = 0.741 29 mol AlCl_3

<em>From Cl_2</em>: Moles of AlCl_3 = 1.11 10 mol Cl_2 × (2 mol AlCl_3/3 mol Cl_2) = 0.740 66 mol AlCl_3

<em>Cl_2 is the limiting reactant</em> because it gives the smaller amount of AlCl_3.

<em>Step 4</em>. Calculate the <em>mass of AlCl_3</em>.

Mass = 0.740 66 mol AlCl_3 × 133.34 g/1 mol AlCl_3 = 98.76 g AlCl_3

The reaction produces 98.76 g AlCl_3.

4 0
3 years ago
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