Congress leader Pawan Khera said clarity was still missing in the paper leak case and this had led to chaos.
Questioning the silence of senior BJP leaders over the issue, he said Modi should answer the questions that were being raised.
"It is unfortunate that the youth of this country are turning (into) cynics. It's a serious matter. Arun Jaitley is quiet, so is Ravi Shankar Prasad ... and Smriti Irani is glum. So let Modiji answer and provide a solution for the youth," he said.
Alleging that the government was "involved in full-time politics and part-time governance", Khera accused it of keeping parents and students in the dark.
"Today, parents and students don't know what the government wants. (Prakash) Javadekarji says that other than those in Delhi and NCR no other child has to appear for a retest," he told reporters here.
But the Jharkhand police, he added, had said the leak affected students across India.
"Why is there no clarity? Don't they understand that they are playing with the future of our youth," he asked.
The Congress leader also referred to the arrest yesterday of Satish Pandey, an alleged ABVP leader who runs a coaching institute in Jharkhand.
"He is linked to the Sangh. Why did he have the paper? There are layers and layers of mysterious information in this," he said, adding that the last few days had seen the "nationalisation of the Vyapam model of the BJP".
"There is an involvement of government or leadership of the BJP. We demand an enquiry which will reveals the roots," he said.
Earlier, the HRD Ministry had said a preliminary enquiry had found that the CBSE paper leak was restricted to Delhi, NCR and Haryana, and if required retests would be held for the Class 10 mathematics paper in these regions in July. The retest for the Class 12 economics paper will be held across India on April 25, it said.
Khera also wondered if something that was leaked through social media platforms such as WhatsApp could be restricted to the Delhi-NCR region.
"Javadekarji, you come from a party where most of its leaders and supporters have gained all their education from WhatsApp university. And you are not understanding that it's scientifically impossible to restrict WhatsApp," he said.
Khera said the recent lathi-charge on a group of young protestors demonstrating against an alleged leak in a Staff Selection Commission (SSC) paper was "criminal" of the government. The government should have had a discussion with the protestors, he said.
The government should agree to a Supreme Court-monitored CBI enquiry into the SSC leak case, he said.