Group the elements into pairs that would most likely exhibit similar chemical properties. it does not matter which pair of elements is pair 1, pair 2, or pair 3, so long as the correct elements are paired. na, o, ne, se, rb, kr

Pair 1 : Na & Rb

Pair 2 : O & Se

Pair 3 :  Ne & Kr

Explanation:

Pair  1 are Group 1 elements in the periodic table. They are electro-positive elements that exhibit metallic properties.

Pair 2 are Group 6 elements in the periodic table. They are electro-negative elements that exhibit non-metallic properties.

Pair 3 are Group 8 or Group 0 elements in the periodic table. They are mainly inert gases.

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.