The process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water.
Answer: Option (c) is the correct answer.
Explanation:
The bottom of pencil is placed at the starting point of scale. Whereas the tip of pencil depicts the end point of its length.
The bottom of pencil is at 0 mm and tip of pencil is at 18.73 mm. The appropriate amount of significant figures is 18.73 mm.
Therefore, we can conclude that out of the given options, pencil is 18.73 mm long.
Answer:
A. there is an isotope of lanthanum with an atomic mass of 138.9
Explanation:
By knowing the different atomic masses of both Lanthanum atoms, we can not tell anything about their occurence in nature. Therefore, all the last three options are incorrect. Because, the atomic mass does not tell anything about the availability or natural abundance of an element.
Now, the isotopes of an element are those elements, which have same number of electrons and protons as the original element, but different number of neutrons. Therefore, they have same atomic number but, different atomic weight or atomic masses.
Hence, by looking at an elements having same atomic number, but different atomic masses, we can identify them as isotopes.
Thus, the correct option is:
<u>A. there is an isotope of lanthanum with an atomic mass of 138.9.</u>
A because if you multiple it, you will be moving the decimal one time
Density = mass / volume
Mass = 5 kg
Volume = 50 cm³
d = 5 / 50
d = 0,1 kg/cm³
