With the increasing growth and popularity of social networking sites, social question and answering has become a venue for individuals to seek and share information. This study evaluates eleven extrinsic factors that may influence the response rate in social question and answering. These factors include the number of followers, the frequency of posting, the number of at-mentioned recipients, whether or not a question contains any at-mentioned verified account, unverified account, hashtag, emoticon, expression of gratitude, repeated punctuation and interjections, as well as the topic and the posting time period of a question. We collected and analyzed over 10,000 questions from Sina Weibo. Eight out of all eleven features were found to significantly predict the number of responses received. We believe that our study is of significant value in providing insights for the design and development of future social question and answering tools, as well as enhancing the collaboration among social network users in supporting social information seeking activities.