This question cannot be answered sensibly. An acre is a measure of area, with dimensions [L2]. A kilometre is a measure of distance, with dimensions [L]. The two measure different things and basic dimensional analysis teaches that you cannot convert between measures with different dimensions such as these without additional information.
However, if you meant square kilometers, then 7,860 acre = 31.80829148 square kilometers.
Answer: 2 km² = 494.210 acres
Seven (7) square km equates to about 1,730(1,729.73767) acres.
Answer: 50 acres = 0.202342 km²
20 acres = 0.08093713 km2
150 acres is 0.607028 km2
Answer: 1 km² = 247.105 acres
Answer: 12,500 acres = 50.5857 km²
580 acres (2.3 km 2)
25 acres is 0.101171 square km
1.38 acres is 0.00558 square km
1 Square Kilometer = 247.105381 Acres
10 acres is 0.0404686 square km