Why is Mars red?

Answer 1

because its red :D plus metal rusts when water is added on it

Answer 2

Have you ever looked up in the sky on a dark clear night to look for Mars? It is not red at all, it looks like an orange star, a bright orange star, and yes- in some areas of the world it might look ochre.

The reddish hue is more observable with a telescope.
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This is a very informative website on Mars. A very good read.
http://www.uapress.arizona.edu/onlinebks/mars/chap02.htm
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Mars is a difficult object to observe. It is a small planet---its diameter is 4,238 miles (6,780 km), only one-half that of the Earth---and it is always more than 140 times farther away from Earth than the Moon. Except during the periods when it is very near the Earth, its disk is always small, and details are not easy to see.
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Mars is only half the diameter of the Earth, yet it never approaches closer than 55.7 million kilometers, or 140 times the distance of the Moon from the Earth. This makes it a difficult object to observe. A 2- or 3-inch (5- or 6.5-cm) telescope will show whatever polar cap is tilted toward the Earth (assuming the cap is large enough at the time) and a few of the main dark areas, such as Syrtis Major. On the whole, however, I consider a telescope of at least 5 inches (7.5 cm) the minimum necessary for a refractor, and 9 inches (22.5 cm) for a reflector---in the latter case, the mirror must possess a perfect figure, and preferably should be of long focus, say f/9 or f/10.

Most observations tend to be made near the oppositions, which occur at intervals of two years and two months. Since some of the most interesting questions about Mars involve time-dependent changes, however, useful studies can be made, and are strongly encouraged, several months before and after opposition, when the disk is as small as 6" or 7" of arc. At the best oppositions, which occur close to the time that Mars passes the perihelion of its orbit, the apparent diameter reaches 25.1". Unfortunately for Northern Hemisphere observers, the planet is then always low in the sky.1

The aphelic oppositions occur in February and March. The disk is much smaller then, of course, only about 14" of arc, but Mars is higher in the sky---a distinct advantage, since it can be observed through less of the Earth's atmosphere. Also, the Martian atmosphere is then generally clearer.

Indeed, as Schiaparelli pointed out long ago, the size of the disk is less important than the transparency of the Martian atmosphere in determining the visibility of minor features. The clarity of the atmosphere, in turn, depends on the season. The Martian dust storm season generally begins around late spring or early summer in the Martian southern hemisphere. At the perihelic oppositions there may be considerable amounts of dust suspended in the air above Mars, which tends to make the markings appear washed out; at the aphelic oppositions the atmosphere is nearly dust-free (though cirrus clouds are frequent), and in general the contrasts of the markings are much stronger.

Answer 3

Mars is red due to the large amounts of iron oxide in the soil of the planet.

Answer 4

because it has a iron oxide layer on it