All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Having a moment of silence is incorrect and a form of Bid‘ah (religious innovation), which was not found during the time of the Prophet, sallallaahu ‘alayhi wa sallam, the Companions or the righteous predecessors . It may be done by some ignorant Muslims who imitate disbelievers.
Those who want to respond to a death should supplicate for the deceased, give charity on their behalf, mention their good deeds and conceal their evil ones, and do similar things that are approved by the Sharee‘ah. However, having a moment of silence is not one of these acceptable things.
Allaah Knows best.