Astronomers have developed several ways to measure the vast distances between Earth and the stars and galaxies. What do you know about two of these techniques?
An astronomical unit (A. U.) is the average distance between the Earth and the Sun.
Our galaxy, the Milky Way, is about 150 light-years across
An astronomical unit is about 93 million kilometers.
Astronomers measure distances to objects which are outside our solar system in light-years.
The A. U. is used to measure distance within our solar system.
A light-year (ly) is the distance that light can travel in one year in a vacuum.

Significant figures are digits read directly from the measuring instrument plus one more digit, which is __ by the observer.

Oxidation-reduction reactions (often called "redox" for short) are reactions that involve the transfer of electrons from one species to another. oxidation states, or oxidation numbers, allow chemists to keep track of these electron transfers. in general, one element will lose electrons (oxidation), with the result that it will increase in oxidation number, and another element will gain electrons (reduction), thereby decreasing in oxidation number. the species that is oxidized is called the reducing agent or reductant. the species that is reduced is called the oxidizing agent or oxidant. to sum up: oxidation = increase in oxidation state = loss of electrons = reducing agent reduction = decrease in oxidation state = gain of electrons = oxidizing agent part a which element is oxidized in this reaction? fe2o3+3co→2fe+3co2 enter the elemental symbol. view available hint(s) is oxidized part b which element is reduced in this reaction? 2hcl+2kmno4+3h2c2o4→6co2+2mno2+2kcl+4h2o enter the elemental symbol. view available hint(s) is reduced

2pos suppose an object in free fall is dropped from a building. its starting velocity is 0 m/s. ignoring the effects of air resistance, what is the speed (in m/s) of the object after falling 3 seconds? give your answer as a positive decimal without units. answer here