Can the deceased hear us when we pray?

There is nothing in scripture to support such a claim. Only God can hear and answer prayers. 

The Bible teaches : At death, humanscease to exist. "Thr dead . . .  are conscious of nothing at all," states Ecclesiastes 9:5.

See also Ecclesiastes 9:6,10.

After death no one lives in any form and there is no afterlife. But the spirits who have lived with the deceased may hear when you pray if they are there.

God never bothers whether people believe in him or not. God’s involvement in human affairs is very rare. God doesn't watch each and every human being at the same time and cannot live with each and everyone to guide them. These works are done by the spirits. God had created different kinds of spirits for various purposes. He had made the spirits to watch, guide and determine the destiny of the human beings from their daily activities, talks and thoughts too. Your past determines your present and your present determines your future. God has given freewill to all creatures including human beings. According to this, all human beings have all right to live a life as they wish. But if it happens to be bad and hurts someone, they have to face the consequences. These consequences are created by spirits. It's a natural system. After death no one lives in any form. Heaven and hell are only for spirits, not for human beings. God is a mystery even to the spirits. Spirits are not eternal beings but their lifetime is long. Spirits are separate elements. A human being during his/her lifetime is living with many spirits which have joined one by one since birth. They are knowledge, skills, feelings, emotions, interests and everything. These spirits are your consciousnesses and memories. Even thoughts are not your own. For example, when you want to take a decision on a subject, one after another the spirits think and you just listen, choose or reject the ideas which they transmit to your mind through your brain in the form of thoughts. Brain is just a media to connect the spirits to your mind. A mind is just a computer's mind. A mind is you. After the destruction of a computer completely you will not get it's mind. The same is the case with the human beings.  A human being doesn't have a spiritual body. Soul is nothing but an energy needed for the functionality of a body. It is not a spirit or anything else. A body's functionality is based on the auto mechanism.  After death all spirits which accompanied a person quit and go to different places searching new bodies. No one lives in any form after death. All human beings are just robots made of flesh and bones and toys of the spirits for their games.

The dead no longer exist 

Apparently so, since the original Christian Church, to which Jesus Christ promised the fullness of God's truth, has taught from the beginning that we can ask the saints in Heaven to intercede (pray) for us.

What is the condition of the dead? What happens to us when we die? The Bible’s clear answer is comforting and reassuring. Watch this video: https://www.jw.org/finder?wtlocale=E&docid=502017858&srcid=share

WHERE DO WE GO WHEN WE DIE? The Bible promises  that one day "Death will be on more." ( Revelation 21:4) But the ransom of Jesus Christ makes it possible  for us to have everlasting life. But people still die. ( Ecclesiastes 9:5) So one of the questions we ask is, What happens to us when we die? The answer to that question is especially important when someone we love dies. We may wonder Where has he gone? Is he watching us? can he help us? Will we ever see him again? Religions answer those questions in different ways. some teach if you are a good person, you go to heaven and if you are a bad person , you burn in hell. some say that when you die you become a spirit and live with your family members who have already died. and others say that after you have died and are judged, you will be reborn, or come back to life with a different body, perhaps as another person or even an animal. Religions seem to teach very different things. But almost all of them teach one basic idea. They teach that when a human dies, a part of him keeps on living. Is that true? ..WHERE DO WE GO WHEN WE DIE?... Jehovah knows what happens to us when we die, and he has told us that when a person dies, his life ends. death is the opposite of life. So when someone dies, his feelings and memories do not keep on living some where else. when we die we can't see, we can't hear, and we can't think anymore. King Solomon wrote that "The dead know nothing at all." The dead cannot love or hate, and "there is no work nor planning nor knowledge nor wisdom in a Grave." ( Read Ecclesiastes 9:5, 6, 10.) And at Psalm 146:4, the Bible tells us that when someone dies, "his thoughts" die. THE TRUTH WILL SET YOU FREE..... The truth about death sets us free from many wrong ideas. The Bible teaches us that the dead don't feel pain or sadness. We can't speak to them, and they can't speak to us. we can't help the dead, and the dead can't help us. They can't harm us, so we don't need to be afraid of them. However, many religions tell us that the dead are alive somewhere and that we can help them if we pay money to priest or those viewed as holy men. But when we know the truth about death, we are not fooled by those lies. Satan uses false religion to lie to us and make us think that the dead are still alive. For example, some religions reach that when we die , a part of us keeps on living somewhere else. Dose your religion teach you that, or dose it teach you what the Bible says about the dead ? Satan uses lies to turn people away from Jehovah. What many religions teach is shocking . For example, some teach that bad people will burn forever in hell. That lie is an insult to Jehovah. He would never allow people to suffer  that way! (Read 1 John 4:8) How would you feel about someone who punishes a child by burning the child's  hands in a fire? You would think he is very cruel. You would not want to get to know him. And that is exactly how Satan wants us to feel about Jehovah! Some religions tell us that when people die, they become spirits. Such religions teach that we must respect and even be afraid of those spirits because they can become either powerful friends or terrible enemies. Many people believe that lie. They fear the dead, so they worship them instead of Jehovah. Remember that the dead cannot feel or sense anything, so we don't have to be afraid of them. Jehovah is our Creator. He is the true God, and we should worship only him. - Revelation 4:11.  When we know the truth about death, we are set free from religious lies. And this truth helps us to understand the wonderful promises that Jehovah has made about our life and our future.  A long time ago, a servant of Jehovah named Job asked: "If a man dies, can he live again?" ( Job 14:14) Is it really possible for  a person who is dead to live again? The answer God gives us in the Bible is very exciting.  for more information JW.ORG

I'm not sure... But still give it a try. 

yes, there spirits can still here us

I like to think, although I'm not religious, that my best friend Madi, who died nearly 3 years ago, can still hear me and that she still communicates with me in some fashion. I know that she cannot physically talk with me anymore but her voice never leaves my head.