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3 years ago

Are used them since made of two or more elements that have been chemically combined is a(n)

1 answer:

5 0

Elements can be chemically combined into compounds, therefore, a compound consists of two or more elements combined, in definite proportions, by chemical means. Compounds may be formed by combining atoms of their constituent elements by ionic bonds or by covalent bonds.

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Hey need help. this is ONE question a 4 part one though. pls help

shusha [124]

I don’t get it. What is the question asking?

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3 years ago

Read 2 more answers

A compound needed for photosynthesis

Pavel [41]

Answer:

Carbon dioxide as well as water are needed for photosynthesis.

Explanation:

8 0

3 years ago

100 POINTS!!!

mixas84 [53]

1) Area of one side of each cube

The area of one side of each cube can be calculated by multiplying the length times the width:

$A=L\cdot W$

where

L = length

W = width

For cube A: $L=1 cm, W=1 cm$

So the area is: $A_A = (1)(1)=1 cm^2$

For cube B: $L=2 cm, W=2 cm$

So the area is: $A_B=(2)(2)=4 cm^2$

For cube C: $L=3 cm, W=3 cm$

So the area is: $A_C=(3)(3)=9 cm^2$

2) Surface area of each cube

The surface area of a cube is given by the sum of the areas of all its faces. Since a cube has 6 identical faces, this means that the total surface area is equal to 6 times the area of one face:

$A=6 A_1$

where

$A_1$ is the area of one face of the cube

For cube A, the area of one face is $A_A=1 cm^2$

So the surface area of cube A is

$A'_A = 6A_A=6(1)=6 cm^2$

For cube B, the area of one face is $A_B=4 cm^2$

So the surface area of cube B is

$A'_B = 6A_B=6(4)=24 cm^2$

For cube C, the area of one face is $A_C=9 cm^2$

So the surface area of cube C is

$A'_C = 6A_C=6(9)=54 cm^2$

3) Volume of each cube

The volume of a cube is obtained by multiplying its length, its width and its height:

$V=L\cdot W \cdot H$

Where:

L = length

W = width

H = height

Moreover for a cube, all the sides have equal length, so $L=W=H$

So the volume can be rewritten as

$V=L^3$

For cube A: L = 1 cm

So the volume is $V_A=(1 cm)^3 = 1 cm^3$

For cube B: L = 2 cm

So the volume is $V_B=(2 cm)^3 = 8 cm^3$

For cube C: L = 3 cm

So the volume is $V_C = (3 cm)^3 = 27 cm^3$

4) Ratio surface area/volume for each cube

In this part, we have to calculate the ratio between surface area and volume of each cube:

$r=\frac{A}{V}$

where

A is the surface area

V is the volume

For cube A, we have:

$A_A = 6 cm ^2$ (surface area)

$V_A=1 cm^3$ (volume)

So the ratio for cube A is:

$r=\frac{6}{1}=6$

For cube B, we have:

$A_B = 24 cm ^2$ (surface area)

$V_B=8 cm^3$ (volume)

So the ratio for cube B is:

$r=\frac{24}{8}=3$

For cube C, we have:

$A_C = 54 cm ^2$ (surface area)

$V_C=27 cm^3$ (volume)

So the ratio for cube C is:

$r=\frac{54}{27}=2$

4 0

3 years ago

U HUCUS 13 HUU

mario62 [17]

Answer:

The correct answer is a the central core and is composed of protons and neutrons.

Explanation:

Nucleus is present in the center of an atom.Nucleus contain positively charged particle proton along with neutron which is neutral.

Due to the the presence of protons nucleus contain positive(+ve) charge.

4 0

3 years ago

Pyridinium is a weak acid having a pKa of 5.2. How much pyridine (the conjugate base of pyridinium) must be added to an aqueous

Whitepunk [10]

Answer:

Amount of pyridine required = 0.0316 M

Explanation:

pH of a buffer solution is calculated by using Henderson - Hasselbalch equation.

$pH=pK_a+log\frac{[Conjugate\ base]}{[weak\ acid]}$

Pyridinium is a weak acid and in the presence of its conjugate base, it acts as buffer.

Henderson - Hasselbalch equation for pyridine/pyridinium buffer is as follows:

$pH=pK_a+log\frac{[Py]}{PyH^+]}$

pH = 4.7

$pK_a=5.2$

$PyH^+$ (Pyridinium)=0.100 M

Substitute the values in the formula

$pH=pK_a+log\frac{[Py]}{PyH^+]}\\4.7=5.2 log\frac{[Py]}{0.100}$

$4.7-5.2=log\frac{[Py]}{0.100} \\-0.5=log\frac{[Py]}{0.100}\\\frac{[Py]}{0.100}=antilog -0.5\\\frac{[Py]}{0.100}=0.316$

$\frac{[Py]}{0.100} =0.316$

[Py]=0.0316\ M

Amount of pyridine required = 0.0316 M

7 0

3 years ago