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3 years ago

Which of the following elements is a metalloid

1 answer:

vladimir1956 [14]3 years ago

4 0

Traditionally they include boron from group 3A, silicon and germanium in group 4A, aresnic and antimony in group 5A and tellurium from group 6A, although sometimes selenium, astatine, polonium and even bismuth have also been considered as metalloids. Typically metalloids are brittle and show a semi-metallic luster.

The six commonly recognised metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Five elements are less frequently so classified: carbon, aluminium, selenium, polonium, and astatine.

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A block of wood has the mass of 180 grams.it is 10 cm long,6 cm wide and 4 cm thick.what is it’s density?

DochEvi [55]

Answer:

0.75 g/cm³

Explanation:

Given data:

Mass of wooden block = 180 g

Length of block = 10 cm

Width of block = 6 cm

Height or thickness = 4 cm

Density of block = ?

Solution:

Volume of block = height × length × width

Volume of block = 4 cm × 10 cm× 6 cm

Volume of block = 240 cm³

Density of block:

density = mass/ volume

d = 180 g/ 240 cm³

d = 0.75 g/cm³

4 0

3 years ago

Use the drop-down menus to complete each sentence.

Ipatiy [6.2K]

Explanation:

Elements that belong to same group contains same number of valence electrons. Hence, they tend to show similar chemical properties.

When we move across a period then number of electrons get added to the same shell. As a result, there will be no increase in size of elements.

Also, metals are the elements that belong to group 1, 2 and d-block elements are also known as metals. Metallic character of elements decreases when we move left to right in a periodic table.

As most reactive metals are placed on the left side of periodic table.

Since, size of elements increases on moving down the group. So, an element is able to easily lose its valence electrons because of less force of attraction between its nucleus and valence electrons.

As a result, there will be increase in reactivity of metals on moving down the group.

Thus, we can conclude that given sentences are as follows.

Elements in the same group have the same number of valence electrons.

Elements in the same period have the same number of electron shells.

Metallic elements become less reactive as you move left to right in a period.

Metallic elements become more reactive as you move top to bottom in a group.

3 0

3 years ago

Read 2 more answers

Cryolite, Na3AlF6(s), an ore used in the production of aluminum, can be synthesized using aluminum oxide. Balance the equation f

dmitriy555 [2]

Answer: The mass of cryolite produced is 51.48 kg

Explanation:

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

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

For aluminium oxide:

Given mass of aluminium oxide = 12.5 kg = 12500 g (Conversion factor: 1 kg = 1000 g)

Molar mass of aluminium oxide = 101.96 g/mol

Putting values in equation 1, we get:

$\text{Moles of aluminium oxide}=\frac{12500g}{101.96g/mol}=122.6mol$

For NaOH:

Given mass of NaOH = 55.4 kg = 55400 g

Molar mass of NaOH = 40 g/mol

Putting values in equation 1, we get:

$\text{Moles of NaOH}=\frac{55400g}{40g/mol}=1389mol$

For HF:

Given mass of HF = 55.4 kg = 55400 g

Molar mass of HF = 20 g/mol

Putting values in equation 1, we get:

$\text{Moles of HF}=\frac{55400g}{20g/mol}=2770mol$

For the given chemical reaction:

$Al_2O_3(s)+6NaOH(l)+12HF(g)\rightarrow 2Na_3AlF_6+9H_2O(g)$

By Stoichiometry of the reaction:

1 mole of aluminium oxide reacts with 6 moles of sodium hydroxide and 12 moles of HF.

So, 122.6 moles of aluminium oxide will react with $(6\times 122.6)=735.6mol$ of sodium hydroxide and $(12\times 122.6)=1471.2mol$ of HF

As, given amount of NaOH and HF is more than the required amount. So, they are considered as an excess reagent.

Thus, aluminium oxide is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of aluminium oxide produces 2 moles of cryolite

So, 122.6 moles of aluminium oxide will produce = $\frac{2}{1}\times 122.6=245.2mol$ of cryolite

Now, calculating the mass of cryolite by using equation 1:

Molar mass of cryolite = 209.94 g/mol

Moles of cryolite = 245.2 mol

Putting values in equation 1, we get:

$245.2mol=\frac{\text{Mass of cryolite}}{209.94g/mol}\\\\\text{Mass of cryolite}=(245.2mol\times 209.94g/mol)=51477.3g$

Converting this into kilograms, we use the conversion factor:

1 kg = 1000 g

So, $51477.3 g\times (\frac{1kg}{1000g})=51.48kg$

Hence, the mass of cryolite produced is 51.48 kg

7 0

3 years ago

Water’s unique properties, high heat capacity, high density, solid phase less dense than liquid phase can be attributed to

Xelga [282]

Answer:

B- The polarity of the molecules and hydrogen bonding between molecules.

Explanation:

Hope this helps:)

4 0

3 years ago

What happens to iron when it melts?

Vilka [71]

As iron heats up, the arrangement of its atoms changes several times before it melts. ... Iron is magnetic at room temperature, and previous work predicted that iron's magnetism favors its open structure at low temperatures, but at 770 degrees Celsius iron loses its magnetism.

plz mark me as brainliest if this helped

8 0

3 years ago

Read 2 more answers

Which of the following elements is a metalloid​

Which of the following elements is a metalloid