How many elements are there in the first column of the periodic table?

What is the relationship between the electric field strength at a point and its distances from the source charge?

diamong [38]

Explanation:

The intensity of electric field from a certain point that is assumed is proportional inversely to the square of distance’s magnitude from source. As one can see the electric field intensity is proportional inversely. Then the increase in magnitude of the space between source charge the electric field intensity decreases.

Since the proportionality is to square of distance, hence change or increase in distance is squared and that many times intensity of electric field decreases. So relation between them is inverse proportionality.

6 0

3 years ago

The amount ofcalcium present in milk can be determined by adding oxalate to asample and measuring the massof calcium oxalate pre

Sauron [17]

<u>Answer:</u> The mass percent of calcium in milk is 0.107 %

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

Given mass of calcium oxalate = 0.429 g

Molar mass of calcium oxalate = 128.1 g/mol

Putting values in equation 1, we get:

$\text{Moles of calcium oxalate}=\frac{0.429g}{128.1g/mol}=0.0033mol$

The given chemical equation follows:

$Na_2C_2O_4(aq.)+Ca^{2+}(aq.)\rightarrow CaC_2O_4(s)+2Na^+(aq.)$

Sodium oxalate is present in excess. So, it is considered as an excess reagent. And, calcium ion is a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of calcium oxalate is produced from 1 mole of calcium ion

So, 0.0033 moles of calcium oxalate is produced from = $\frac{1}{1}\times 0.0033=0.0033mol$ of calcium ions

Now, calculating the mass of calcium ions by using equation 1, we get:

Moles of calcium ions = 0.0033 moles

Molar mass of calcium ions = 40 g/mol

Putting values in equation 1, we get:

$0.0033mol=\frac{\text{Mass of calcium ions}}{40g/mol}\\\\\text{Mass of calcium ions}=(0.0033mol\times 40g/mol)=0.132g$

To calculate the mass percentage of calcium ions in milk, we use the equation:

$\text{Mass percent of calcium ions}=\frac{\text{Mass of calcium ions}}{\text{Mass of milk}}\times 100$

Mass of milk = 125 g

Mass of calcium ions = 0.132 g

Putting values in above equation, we get:

$\text{Mass percent of calcium ions}=\frac{0.132g}{125g}\times 100=0.107\%$

Hence, the mass percent of calcium in milk is 0.107 %

7 0

3 years ago

Which of the following is not equal to 120 centimeters?

tia_tia [17]

<h3>Answer:</h3>

0.012 dekameters (dkm)

<h3>Explanation:</h3>

<u>We are given;</u>

120 centimeters( cm).

Required to identify the measurements that is not equivalent to 120 cm.

Centimeters are units that are used to measure length together with other units such as kilometers(km), meters (m), millimeters (mm), dekameters (dkm), etc.

These units can be inter-converted to one another using suitable conversion factors.

To do this, we are going to have a table showing the suitable conversion factor from one unit to another.

Kilometer (km)

10

Decimeter (Dm)

10

Hectometer (Hm)\

10

Meter (m)

10

Dekameter (dkm)

10

Centimeter (cm)

10

Millimeter (mm)

Therefore;

To convert cm to km

Conversion factor is 10^5 cm/km

Thus;

120 cm = 120 cm ÷ 10^5 cm/km

= 0.0012 km

To convert cm to dkm

Conversion factor is 10 cm/dkm

Therefore,

120 cm = 120 cm ÷ 10 cm/dkm

= 12 dkm

To convert cm to m

The suitable conversion factor is 10^2 cm/m

Thus,

120 cm = 120 cm ÷ 10^2 cm/m

= 1.2 m

To convert cm to mm

Suitable conversion factor is 10 mm/cm

Therefore;

120 cm = 120 cm × 10 mm/cm

= 1200 mm

Therefore, the measurement that is not equal to 120 cm is 0.012 dkm

4 0

3 years ago

What are the physical properties of liquid bleach

Archy [21]

I think it is Sodium,hypochlorite

6 0

3 years ago

What is an indicator that a chemical change has occurred?

Aleks04 [339]

Answer:

That something has changed chemically

Explanation:

Uh...Google it

6 0

4 years ago

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