Which feature is used to classify galaxies? age, color ,shape, size wich one need asap

The correct answer is Shape.

Explanation:

Galaxies are defined as the system of million or billions of stars along with gas and dust held together by gravitational attraction.

These are classified as 3 types on the basis of its shape:

1. Spiral galaxy: It is defined as the galaxy in which stars and gas clouds are located mainly in one or more spiral arms. Example: Milky Way

2. Elliptical galaxy: It is defined as the galaxy which has ellipsoidal shape and a smooth, featureless image. Example: M-110.

3. Irregular galaxy: It is defined as the galaxy that does not have any distinct regular shape. Example: Irr-I galaxy.

Hence, the correct answer is Shape.

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.