Answer:
we can reach the same conclusions by applying different experimental and observational procedures
Explanation:
The scientific method is a process that can be summarized in the following steps: 1-to raise a question, 2-to make a hypothesis, 3-to obtain data from observations and/or experiments, and finally, 4-to obtain conclusions that enable to confirm (or reject) the hypothesis. The scientific method is flexible because it is not necessary to follow 'stringent' guidelines in order to reach the same conclusions. In consequence, the predictions derived from such results can be tested again to determine the veracity of the results.
Answer: The objects that are luminous are a lamp and a computer screen
Explanation: This is because these two objects shine or glow with light.
Answer:
Explanation:
Sodium and potassium are present in group 1A. Both are alkali metals.
The atomic number of sodium is 11 and potassium is 19. Sodium is present in period 3rd while potassium is present in period 4th.
Electronic configuration of sodium:
Na₁₁ = 1s² 2s² 2p⁶ 3s¹
K₁₉ = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
It can be seen in electronic configuration that in case of sodium the valance electron is present in third energy level while in case of K outer most electron is present in 4th energy level. So atomic structure of sodium has three energy level and K has four energy level that's why radius of potassium is greater than sodium because its the distance from center to outer most electronic shell.
Moreover as we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased.
Answer:
d= 50.23 g/cm³
Explanation:
Given data:
radius = 137.9 pm
mass is = 5.5 × 10−22 g
density = ?
Solution:
volume of sphere= 4/3π r³
First of all we calculate the volume:
v= 4/3π r3
v= 1.33× 3.14× (137.9)³
v= 1.33 × 3.14 × 2622362.939 pm³
v= 1.095 × 10∧7 pm³
v= 1.095 × 10∧-23 cm³
Formula:
Density:
d=m/v
d= 5.5 × 10−22 g/ 1.095 × 10∧-23 cm³
d= 5.023 × 10∧+1 g/cm³
d= 50.23 g/cm³