Mr.Neeraj pahuja,

No.1 Go to Sino Center to take No. 238X. It will take you to China Ferry Terminal.
No.2 Hong Kong Heritage Museum: take MTR from Mong Kok to Che Kung Temple and get out at Exit A. Then walk around 5 minutes to Hong Kong Heritage Museum.
No.3 Hong Kong Museum of Art: take mtr from Mong Kok to Tsim Sha Tsui MTR Station and then walk to East Tsim Sha Tsui MTR Station and get out at Exit J.
No.4 Hong Kong Museum of Coastal Defence: take mtr from Mong Kok to Shau Kei Wan and get out at Exit B2. Walk along Shau Kei Wan Main Street East, cross the road upon reaching Tung Hei Road, then walk up hill for 5 mins.
No.5 Hong Kong Museum of History: take mtr from Mong Kok to MTR Tsim Sha Tsui Station Exit B2 and walk along Cameron Road towards East Tsim Sha Tsui for 20mins.
No.6 Hong Kong Science Museum: take MTR from Mong Kok to Tsim Sha Tsui Station Exit B2 and walk along Cameron Road towards East Tsim Sha Tsui for 8 mins.
No.7 Hong Kong Space Museum: take mtr from Mong Kok to Tsim Sha Tsui and walk to East Tsim Sha Tsui MTR Station. Exit J and walk about 10 mins to the museum.
No.8 To the airport: Go to 639 Nathan Road outside Grand Tower to take A21 airport shuttle bus. It costs HK$33.