elements, compounds and mixtures​

Answer:

2

Explanation:

Oxygen has 6 electrons in its valence shell.  Since an atom can have a maximum of 8 electrons in the valence shell, oxygen has 2 empty spots in its valence.  This means that oxygen can make 2 single covalent bonds.

The maximum number of covalent bonds that an oxygen atom with atomic number 8 can make with hydrogen is: 2.

Valency can be defined as a measure of the combining power of a chemical element with other atoms to form a molecule or chemical compound.  Typically, valency is measured by the amount of hydrogen atoms that a chemical element can combine with or displace to form a molecule or chemical compound.

Valence electrons can be defined as the number of electrons present in the outermost shell of an atom. Valence electrons are used to determine whether an atom or group of elements found in a periodic table can bond with others.

From the periodic table, we know that an oxygen atom has an atomic number of eight (8). Thus, oxygen has six (6) electrons in its valence shell and two (2) empty shells to form a covalent bond with hydrogen.  

Generally, the maximum number of electrons an atom can hold in its valence shell is eight (8) and since oxygen has has six (6) electrons in its valence shell; it ultimately implies that the maximum number of covalent bonds that an oxygen atom with atomic number of eight (8) can make with hydrogen is two (2) covalent bonds.

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Answer:

See explanation

Explanation:

A salt is made up of homogeneous particles while sand is made up of heterogeneous particles. Salt is a crystalline substance while sand is a coarse substance.

If salt and sand are mixed with water, salt forms a solution with water, hence, salt cannot be caught on filter paper. However, sand does not form any chemical specie with water hence it is caught on the filter paper as a solid.

Answer:

The elixir of life, also known as elixir of immortality and sometimes equated with the name philosopher's stone, is a potion that supposedly grants the drinker eternal life and/or eternal youth. This elixir was also said to cure all diseases.

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]Density = \frac{mass}{volume} [/tex]

From the question

mass = 6.356 g

volume = 2.56 cm³

Substitute the values into the above formula and solve.

That's

[tex]Density = \frac{6.356}{2.56} \\ = 2.4828125[/tex]

We have the final answer as

Density = 2.48 g/cm³

Hope this helps you

Answer:

Never pour water into acid but acid into water

Explanation:

If water is poured into extremely concentrated acid/bases, the rate of volatility and exothermic reaction is too rapid and might cause a chemical eruption, leading to acid burns.

Safety precautions hence dictate the reverse is practiced.

I believe this is a clear answer.

Answer:

Strontium, as opposed to other elements on the periodic table (with the exception of others in the same group/column i.e., the vertical direction), is a good substitute for Calcium because they are in the same group.

Explanation:

This is because elements of the same group behave similarly and have similar properties. This is due to the fact that elements of the same group (in the vertical direction) have the same number of valence electrons.

Answer:

1) higher

2) lower

1) energy

Explanation:

hope this helps you.

I would really like a brainliest :D

thank you and have a nice day.

Answer:

1) higher

2) lower

1) energy

Explanation:

Isotopes of the same element have the same atomic number and different mass numbers. Hence, option C is correct.

Isotopes are defined as chemical species which have the same number of protons but differ in the number of neutrons.

It can also be said that they are the chemical species of the same element which have the same atomic number but have different mass numbers.

For Example, C12 and C14 are the isotopes of carbon elements, which have the same atomic number but a different mass numbers.

Hence, option C is correct.

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Answer:

True

Explanation:

I guessed XD But I also used Google and that's what I got

Answer:

This question is incomplete

Explanation:

This question is incomplete. However, the period of the periodic table are the horizontal (left to right) rows in the periodic table. Elements in the same period have the same number of electron shells. There are seven periods in the periodic table.

The periodic table of elements is the table that contains all chemical elements arranged according to there atomic number. Atomic number is the number of protons present in the nucleus of an atom.

Answer:

0.24%

Explanation:

The following data were obtained from the question:

Measured value = 42.1 g

Actual value = 42 g

Percentage error =?

Percentage error can be obtained by using the following formula:

Percentage error = |Measured value – Actual value | / Actual value × 100

With the above formula, we can obtain the percentage error as follow:

Measured value = 42.1 g

Actual value = 42 g

Percentage error =?

Percentage error = |42.1 – 42| / 42 × 100

Percentage error = 0.1/42 × 100

Percentage error = 10/42

Percentage error = 0.24%

Therefore, the percentage error is 0.24%

Answer:

4.11x10⁶Joules

10.04Cal

Explanation:

Calories and joules are units of energy used in several fields of science.

4184Joules are equal to 1 Cal.

In joules, 982 calories are:

982 Calories * (4184 J / 1 Cal) =

In the same way, 4.2x10⁴ Joules are:

4.2x10⁴J * ( 1Cal / 4184J) =

Answer:

There's 34,000,000,000 nanograms in 34g.

Explanation:

U can write it like 3.4e+10.

Hope I helped ya.

< Sarah >

Answer:

0.0069

Explanation:

When converting between scientific notation try to remember that moving the decimal place to the left is positve and to the right is negative

Since you are changing from scientific to standard you will need to move to the left from the decimal point, making your answer 0.0069

Answer:

The inner core is a hot, dense ball of (mostly) iron. It has a radius of about 1,220 kilometers (758 miles). Temperature in the inner core is about 5,200° Celsius (9,392° Fahrenheit). The pressure is nearly 3.6 million atmosphere (atm).

Explanation:

Answer:

ITS A. (Give me brainliest!!)

When a glass or a watermelon is moved, the volume stays the same as they are in a fixed shape and the volume of a solid state. Option A correct.

A solid-state is a state of matter in which the molecules of matter are closely packed with each other with the maximum molecular force of attraction for a fixed shape.

Glass and watermelon are fixed in shape as they are made before and volume is also fixed and the molecules are fixed in definite shape and the volume cannot be changed.

Therefore, Option A correct. When a glass or a watermelon is moved, the volume stays the same as they are in a fixed shape and the volume of a solid state.

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Answer:

1.45 kg

Explanation:

common sense ok

Answer:

1450 grams are in 1.45 kilograms

Answer:

The reactivity of group 1 elements increases as you go down the group because: the atoms become larger. the outer electron becomes further from the nucleus. the force of attraction between the nucleus and the outer electron decreases.

Explanation:

plz if this helped name me brainliest

Humidity refers to the amount of water vapor in the air accurately describes it.

This can be defined as the gaseous phase of water as a result of heating in the atmosphere.

The amount of the water vapor in air is what is referred to as humidity which makes option D the most appropriate choice.

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Answer:

[See Below]

Explanation:

✦ A beaker of liquid would measure the volume of a liquid.

✦ A graduated cylinder is good for estimating the volume of a liquid.

✦ You'd most likely use a tape measure to measure the wall length and width.

~Hope this helps Mate. If you need anything feel free to message me.

The value of mass is 680 g.

It is defined as mass per unit volume.

Given:-

[tex]Density=13.6\ g/cm^{3} \\Volume=50\ mL[/tex]

Calculate mass as follows:-

[tex]Density=Mass/Volume\\13.6\ g/cm^{3} = Mass/50.0\ mL\\Mass=13.6\ g/cm^{3} \times50.0\ mL[/tex]

Relationship used:-

[tex]1\ cm^{3} =1\ mL[/tex]

[tex]Mass=680\ g[/tex]

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Answer:

2 significant figures.

Explanation:

Significant Figures Rules:

1. Anything that isn't a zero is a sig fig

2. If a decimal point comes after the ones digit, everything before the decimal is counted as sig fig (i.e 2000. would be 4 sig figs).

3. If we are dealing with small decimals, the zero before and after the decimal (i.e 0.002) is a placeholder and is not counted as sig figs.

4. Any zeros between 2 significant digits is considered in sig figs (i.e 2002 would be 4 sig figs)

Since we are dealing with 87000, we see that we have no decimal point. That means our only sig figs are 8 and 7, which equals 2 sig figs.

Answer:

D

Explanation:

because it's saying the diet soda has more calories then regular soda it's like someone claimed you of doing something you didn't do and they don't know that

Answer:

homogeneous mixture

Answer:  The size, mass, and arrangement of atoms affect the density of a substance. How might these factors work together to cause a substance to have a high density? A substance with smaller more massive atoms that are close together is going to have a higher density.

Explanation:

Answer:

3.8

Explanation:

Answer: The answer is option B

1,000-2,000

Explanation:

Answer:

72.22 g

Explanation:

975 mL Mercury× 13.5 g/mL = 72.22 g