In his two days of testimony before Congress, Facebook CEO Mark Zuckerberg told lawmakers he would need to come back with answers to several of their questions at a later date. The list of still-to-be-addressed issues is a long one, The New York Times reported. Here's what the embattled founder pledged to look into.

The transfer of data to third parties
In a recent Recode survey, 56 percent of Americans said they trust Facebook the least out of any major tech company. It was Zuckerberg's job in the hearing to provide reassurance in the wake of the news that political data firm Cambridge Analytica harvested information from more than 87 million Facebook users to create voter profiles that were used by Donald Trump's presidential campaign.

Zuckerberg said he would let lawmakers know if his team finds any new examples of improper transfer of data to a third party. He will also survey how many outside developers from his team had been audited to make sure they were following rules laid out by Facebook and check whether Facebook employees ever worked with Cambridge Analytica to help the Trump campaign in 2016.

Tech industry regulation 
Zuckerberg was tasked with figuring out how to have a broad discussion about how the tech industry should be regulated, in order to avert similar privacy and security issues in the future. 

Making the tech industry more diverse
The Facebook chief will look into an idea of convening a meeting of technology firms to boost racial diversity in the industry, and said he would come back with data on employee retention at Facebook broken out by race.

Zuckerberg also said he would report back to lawmakers on other issues including protecting minors online, finding ways to regulate fake accounts, and bringing broadband to rural areas.