1. the of the hubble space telescope is better for shorter (bluer) wavelengths of light than for longer (redder) wavelengths of light2. the large research observatories on mauna kea use giant separate the various colors of light, allowing astronomers to determine stellar composition and may other stellar properties.4. the twin 10-m keck telescopes can work together to obtain better angular resolution through a technique known as . the chandra x-ray observatory focuses x rays with mirrors.6. a 10-meter telescope has a larger than a 4-meter telescope.7. galileo's telescope designs using lenses were examples of

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2