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3 years ago

Metals and nonmetals all lesson explanation for class 8

Chemistry

1 answer:

WINSTONCH [101]3 years ago

7 0

Answer:

Metalloids elements whose properties are intermediate between those of metals and solid nonmetals or semiconductors.

Some examples:

Chemical element.

Boron.

Semiconductor.

Arsenic.

Silicon.

Selenium.

Antimony.

Germanium.

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Match the atoms which might substitute for one another. Match the items in the left column to the items in the right column.

valkas [14]

Atoms which might substitute for one another can be found in the same column in the periodic table.
So, since Si and C are found in the same column, they can substitute each other.
1. Si = C
2. K = Na
3. Nb = V
4. Cu = Ag
5. P = As
6. Mg = Ca

8 0

3 years ago

Read 2 more answers

A single 250 gram

Gala2k [10]

2.2 x 10^-2

0.055 / 250 = 0.00022 - This would be 2.2 x 10^-4, but the question is asking for percent, not proportion, so multiply by 100% to get the percentage.

0.00022 * 100% = 0.022% = 2.2 * 10^-2

6 0

3 years ago

Consider the statement: "Copper is a red-brown element obtained from copper sulfide ores by heating the ores in air, which forms

Misha Larkins [42]

Answer:

1, just I) color.

Explanation:

Physical properties are the properties that can be observed without changing the composition of a substance, such as color, temperature, density, and boiling point.

A physical change is a change in the substance that only modifies its aggregation state, such as solidification, and boiling.

Chemical properties are the properties that need a reaction to being observed, such as the combustibility, which needs a combustion reaction to being quantified.

When a chemical reaction occurs, and the composition of the substance change, it's a chemical change.

So, the heating copper with carbon is a chemical reaction, and purification by electrolysis is too. Color is the only physical property.

4 0

4 years ago

A piece of wood has a labeled length value of 63.2 cm. You measure its length three times and record the following data: 63.1 cm

Ulleksa [173]

Percent error (%)= $\frac{\left | Accepted value - Measured value \right |}{Accepted value}\times 100$

Accepted value is true value.

Measured values is calculated value.

In the question given Accepted value (true value) = 63.2 cm

Given Measured(calculated values) = 63.1 cm , 63.0 cm , 63.7 cm

1) Percent error (%) for first measurement.

Accepted value (true value) = 63.2 cm, Measured(calculated values) = 63.1 cm

Percent error (%)= $\frac{\left | Accepted value - Measured value \right |}{Accepted value}\times 100$

$Percent error = \frac{\left | 63.2 - 63.1 \right |}{63.2}\times 100$

$Percent error = \frac{0.1}{63.2}\times 100$

$Percent error = 0.00158\times 100$

Percent error = 0.158 %

2) Percent error (%) for second measurement.

Accepted value (true value) = 63.2 cm, Measured(calculated values) = 63.0 cm

Percent error (%)= $\frac{\left | Accepted value - Measured value \right |}{Accepted value}\times 100$

$Percent error = \frac{\left | 63.2 - 63.0 \right |}{63.2}\times 100$

$Percent error = \frac{0.2}{63.2}\times 100$

$Percent error = 0.00316\times 100$

Percent error = 0.316 %

3) Percent error (%) for third measurement.

Accepted value (true value) = 63.2 cm, Measured(calculated values) = 63.7 cm

Percent error (%)= $\frac{\left | Accepted value - Measured value \right |}{Accepted value}\times 100$

$Percent error = \frac{\left | 63.2 - 63.7 \right |}{63.2}\times 100$

$Percent error = \frac{\left | -0.5 \right |}{63.2}\times 100$

$Percent error = \frac{(0.5)}{63.2}\times 100$

$Percent error = 0.00791\times 100$

Percent error = 0.791 %

Percent error for each measurement is :

63.1 cm = 0.158%

63.0 cm = 0.316%

63.7 cm = 0.791%

7 0

4 years ago

What advice would you give a person who handles hydrogen and oxygen in their workplace?

Murljashka [212]

Regard the principle of utilization of two gas.

Make a consistent control of hardware containing gas.

Make a consistent control of weight diminishing valves giving gas.

No smoking zone.

3 0

3 years ago

Metals and nonmetals all lesson explanation for class 8​

Metals and nonmetals all lesson explanation for class 8