HEY DEAR..
The particles of light known as photon.
HOPE ITS HELPFULL
Answer: See description
Explanation:
Kepler's laws have three principal points:
1. planets orbit the sun in elliptical paths
2. the orbial period is related to the orbital distance by 
where T is the orbital period and d is the orbital distance, T is in years and d is measured in units of the earth sun distance.
3. planets closer to the sun move faster than planets far away from it.
Newton:
Newton discovered that there is a consequence to the gravity exerted by objects: mass, the heavier the planet, the more gravitational force it posseses ( thats why we orbit the sun)
with the gravitational force
newton discovered the inverse-quadratic relationship between the distance of the planets and the acceleration exerted by the force one could exert on another.
Kepler's laws were mostly based on observed evidence with quantitative relationships between the mentioned variables. Newton's laws are based on calculus and symbolic equations. While Kepler's mode is basic, Newton took another step in and build a more general model for gravity (which was improved by general relativity later). In a nutshell Newton proved the scientific causes for Kepler's laws...
Answer 1
The sample will dissolve in more than 1 minute.
Explanation :-
Generally Solubility and rate of solubility of substances increase with the increase in temperature. So lower the temperature less fast will it dissolve in the same amount of water.
Since at 50 C it takes 1 minute to dissolve, at 20 C which is lower temperature it will take more time to dissolve.
Answer 2
Transition metals
Explanation:-
Hardness depends on the extent of metallic bonding for metals. More the number of electrons more the metallic bonding.
Alkali metals with just 1 valence electron have weak metallic bonding. Alkaline earth metals have just 2 valence electrons. Transition elements has more electrons in penultimate shell and valence shell than lanthanides. Transition metals with most metallic bonding are the hardest