Umm im looking to practice for my quiz and I cant check if my answers are correct can someone tell me the correct answer

1. According to the fossil record, the first LAND plants were most likely pine trees. moss and ferns. flowering plants. 2. Scien

Lynna [10]

Answer:

It is true that earth was once covered with oceans and little dry land.

Explanation:

Over the course of around four billion years, the Earth's oceans have lost about a quarter of their original mass. Today the atmosphere is rich in oxygen, which reacts with both hydrogen and deuterium to recreate water, which falls back to the Earth's surface. So the vast bulk of the water on Earth is held in a closed system that prevents the planet from gradually drying out. According to the researchers, the continents emerged relatively suddenly from an ocean that covered 95 percent of the Earth's surface. The appearance of large masses of dry land would have caused more extreme weather, changes in ocean currents and the emergence of proper seasons. In turn, these environmental changes may have led to rise in atmospheric oxygen that enabled the explosion of new life forms around 500 million years ago.

7 0

3 years ago

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A sample of gas has a volume of 3.75 L at a temperature of 25°C and a pressure of 1.15 atm. What will the volume be at a tempera

omeli [17]

Answer: V = 5.1 L

Explanation: To find the new volume, we will use the formula of Combined Gas Law and derive V2. We also need to convert first the temperature in Kelvin and convert torr to atm ( 1 atm = 760 torrs ).

Solution attached.

5 0

2 years ago

2. The Density of Water is 1.0000g/cm3. Based on this property of water,

Vanyuwa [196]

Answer:

if the object sank then that object has a greater density then water. if the object floated then its density is lower then water.

Explanation:

lets say object 1 has a density of 24/cm3. the density is greater then water (1.0000g/cm3) so it would sink. now lets say object 2 has a density of 0.79383g/cm3 since it's less then the density of water (1.0000g/cm3) it would float.

7 0

2 years ago

Calculate the acid dissociation constant of a weak monoprotic acid if a 0.5M solution of this acid gives a hydrogen-ion concentr

RUDIKE [14]

Let the acid be HA.
The chemical formula for this acid will be the following:

$HA \rightleftharpoons H^{+}+A^{-}$

The formula for the acid dissociation constant will be the following:

 $K_a= \dfrac{[H^+][A^-]}{[HA]}$

We know [H+]=0.0001 (it's given).
However, we must find [A-] and [HA] in order to solve for the constant.

We find that [A-]=[H+] by using a electroneutrality equation.
Also, we can create a concentration equation to find [HA].

 $0.5M=[A^-]+[HA]$
$[HA]=0.5M-[A^-]$

Now, we can find the acid dissociation constant.

 $K_a= \dfrac{[H^+][A^-]}{0.5M-[A^-]}$

$= \dfrac{0.0001*0.0001}{0.5-0.0001} = 2.0*10^{-8}$

4 0

2 years ago

Describe the energy in coal and the way in which it’s converted to electrical energy. Write 50 to 100 words.

devlian [24]

Answer:

Coal contains chemical potential energy

Explanation:

Chemical species are known to contain chemical energy. Chemical energy is contained in chemical bonds in a chemical substance.

Since energy can neither be created nor destroyed, energy contained in chemical bonds can be transformed from one form to another. Coal contains chemical energy.

One of the ways of generating electricity is the combination of fossil fuels. This involves the conversion of chemical energy to heat energy. The steam produced is used to turn a turbine. The turning off the turbine implies a conversion of heat to mechanical energy. The turning of the turbine now produces electrical energy.

4 0

2 years ago