b) compound
c) isotope
d) proton
e) molecule
Answer:
A
Explanation:
An element is a substance that cannot be broken down into simpler substances using ordinary chemical procedures. To disintegrate an element, procedures like nuclear reactions needed to be used.
In fact, it was thought of that the elements are indivisible during the days of Dalton, but advances in science and technology has shown that these elements could be broken down albeit not easily
An element is a substance that cannot be broken down into other substances by ordinary chemical methods. It is the basic unit of all matter. Examples of elements include gold, silver, and carbon.
A substance that cannot be broken down into other substances by ordinary chemical methods is called an element. This is because elements are the fundamental materials of which all matter is composed. For instance, gold, silver, and carbon are examples of elements. Unlike compounds, isotopes or molecules, an element is made up of the same type of atom and cannot be decomposed into simpler substances by any ordinary chemical processes.
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True
False
A perpetual motion machine is an invention that has only worked a few times in history.
True
False
Thermal pollution occurs when factories use water to cool down their heated machinery, and then release the heated water into rivers and oceans.
True
False
Answer:
Crushing or grinding increases the surface area of the salt that is exposed to the molecules of water. Stirring increases the speed at which the particles of salt come in contact with the water molecules.
(2) NO (4) HCl
Answer: (1) CO
Explanation: A molecule is said to be polar when it has atoms with different electronegativities. The more is the difference in electronegativity, the more polar is the bond.
Electronegativity of carbon and oxygen are 2.5 and 3.5 respectively. Thus difference is (3.5-2.5)=1.0.
Electronegativity of hydrogen and Iodine are 2.1 and 2.7 respectively. Thus difference is (2.7-2.1)=0.6.
Electronegativity of nitrogen and oxygen are 3.0 and 3.5 respectively. Thus difference is (3.5-3.0)=0.5.
Electronegativity of hydrogen and chlorine are 2.1 and 3.0 respectively. Thus difference is (3.0-2.1)=0.9.
Thus as the highest difference of electronegativity is among carbon and oxygen, CO is the most polar.
Which formula represents a molecule with the most polar bond? (1) CO (3) HI (2) NO (4) HCl
The formula that represents a molecule with the most polar bond is the HCl, hydrochloric acid. The answer is number 4.
(2) They differ in their properties, only.
(3) They differ in their molecular structure and properties.
(4) They do not differ in their molecular structure or properties.
Answer: Option (3) is the correct answer.
Explanation:
When an element exists in two or more different physical forms then they are known as allotropes.
For example, diamond and graphite are both allotropes of carbon.
In graphite, carbon atoms are joined together in sheets of six sided lattice. Whereas in diamond, carbon atoms are joined together in four cornered lattice.
Therefore, as these allotropes are made up of same element so they have similar chemical properties but different physical properties like melting point, boiling point etc.
Also, both of them have different molecular structure.
Thus, we can conclude that the statement the differ in their molecular structure and properties correctly describes diamond and graphite.
The equation for power is,
Power
Where P is power is Watts
I is current in Amperes
V is voltage in volts
Given, power of the camcorder = 16 Watts
Output voltage from its battery = 8 Volts
Calculating the current in Amperes from power and voltage,
I =
= 2 A
Therefore the current used will be 2 A.
Power is defined as product of current multiplying voltage, that is
P=I×V
Here, P is the power,
I is the current
While V is the voltage
Here,
P is 16 watt
V is 8 volt
I is the current, that needs to be determined,
Putting the values in the equation
16=I× 8
I=2
So, When a camcorder has a power rating of 16 watts. If the output voltage from its battery is 8 volts, what current is 2 A